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5331bac6e01dc8056b7661fc927deaa92fe2e0d899403b621b9f569bd790ece2
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2026-01-07T00:00:00-05:00
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How to obtain slow roll inflation driven by non-linear electrodynamics
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arXiv:2503.19679v2 Announce Type: replace-cross Abstract: We establish for the first time the conditions that must be imposed on the action for a magnetic universe in a theory of non-linear electrodynamics in order to have an asymptotically de Sitter initial state followed by a slow roll inflationary phase. We show that models so far proposed in the literature do not allow for a prolonged inflationary phase consistent with observations. We construct a Lagrangian that reduces to the Maxwell one in weak field; this is the only class of models that satisfies the required conditions for slow roll in the early Universe.
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https://arxiv.org/abs/2503.19679
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Academic Papers
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bc5f428e6ea140473934ad2be78bcddf67a0a8d8f60a7d1922797cf7f0527f30
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2026-01-07T00:00:00-05:00
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Physics beyond the Standard Model with the DSA-2000
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arXiv:2505.23892v2 Announce Type: replace-cross Abstract: The upcoming Deep Synoptic Array 2000 (DSA-2000) will map the radio sky at $0.7-2$ GHz ($2.9 - 8.3 \, \mu$eV) with unprecedented sensitivity. This will enable searches for dark matter and other physics beyond the Standard Model, of which we study four cases: axions, dark photons, dark matter subhalos and neutrino masses. We forecast DSA-2000's potential to detect axions through two mechanisms in neutron star magnetospheres: photon conversion of axion dark matter and radio emission from axion clouds, developing the first analytical treatment of the latter. We also forecast DSA-2000's sensitivity to discover kinetically mixed dark photons from black hole superradiance, constrain dark matter substructure and fifth forces through pulsar timing, and improve cosmological neutrino mass inference through fast radio burst dispersion measurements. Our analysis indicates that in its planned five year run the DSA-2000 could reach sensitivity to QCD axion parameters, improve current limits on compact dark matter by an order of magnitude, and enhance cosmological weak lensing neutrino mass constraints by a factor of three.
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https://arxiv.org/abs/2505.23892
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Academic Papers
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a34a649ac2ae67577f8a46e5372310551bdfc592156b4ed8c2b1a2902fc5f7d9
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2026-01-07T00:00:00-05:00
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Freeze-in production of scalaron dark matter in $f(R)$ gravity
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arXiv:2506.06436v2 Announce Type: replace-cross Abstract: We demonstrate that the scalaron, a scalar degree of freedom, emerging from the $f(R)$ theory of gravity, can account for the observed dark matter (DM) abundance if its mass is around the MeV scale, to ensure its cosmological stability. Focusing on two well-known $f(R)$ gravity models, we systematically show that if scalaron production proceeds via the freeze-in mechanism, the right relic abundance is satisfied over a very narrow window of reheating temperature $10^{14}\lesssim T_{\rm rh}\lesssim 10^{16}$ GeV. We delineate the viable parameter space of the $f(R)$ models consistent with the observed DM abundance, and highlight relevant experimental constraints from searches targeting DM decay signatures.
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https://arxiv.org/abs/2506.06436
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Academic Papers
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d5389d37545700f3e2736cd0cae3ca3ff00080a7d6a1d56665bcc6f18feeeba8
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2026-01-07T00:00:00-05:00
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Implications of DESI for Dark Matter & Cosmic Birefringence
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arXiv:2506.12589v2 Announce Type: replace-cross Abstract: We explore an interacting dark matter (DM)-dark energy (DE) framework that naturally yields an effective dynamical DE equation of state crossing the phantom barrier at early times, as indicated by recent DESI data, while also accounting for the observed isotropic rotation of the cosmic microwave background (CMB) linear polarization. Within this unified framework, we also explain the DM relic abundance without introducing additional fields or couplings. Depending on the DE potential, we identify two viable scenarios: a superheavy freeze-in DM requiring a high reheating temperature, or a strongly interacting dark sector with a GeV-TeV scale thermal DM candidate.
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https://arxiv.org/abs/2506.12589
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Academic Papers
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9c0fce7a80818ea0e2397943574c23382a735af87662a5196a6579fec8bb640d
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2026-01-07T00:00:00-05:00
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Classification of $f(R)$ Theories Of Inflation And The Uniqueness of Starobinsky Model
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arXiv:2507.02637v2 Announce Type: replace-cross Abstract: We classify $f(R)$ theories using a mathematical analogy between slow-roll inflation and the renormalization-group flow. We derive the power spectra and spectral indices class by class and compare them with the latest data. The framework used for the classification allows us to determine the general structure of the $f(R)$ functions that belong to each class. Our main result is that only two classes survive. Moreover, we show that the Starobinsky model is the only polynomial $f(R)$ that can realize slow-roll inflation. In fact, all other polynomials belong to a special class that can only realize constant-roll inflation, at least far enough in the past. We point out some of the issues involved in considering a smooth transition between constant-roll and slow-roll inflation in this class of models. Finally, we derive the map that transforms the results from the Jordan frame to the Einstein frame.
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https://arxiv.org/abs/2507.02637
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Academic Papers
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d2c703bc7f7ac9d127867412fac4bd10a8dcf0ab03e6838029b0004543646ead
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2026-01-07T00:00:00-05:00
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Beyond $\rho^{2/3}$ Scaling: Microscopic Origins and Multimessengers of High-Density Nuclear Symmetry Energy
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arXiv:2510.05508v2 Announce Type: replace-cross Abstract: Nuclear symmetry energy $E_{\mathrm{sym}}(\rho)$ encoding the cost to make nuclear matter more neutron rich has been the most uncertain component of the EOS of dense neutron-rich nucleonic matter. It affects significantly the radii, tidal deformations, cooling rates and frequencies of various oscillation modes of isolated neutron stars as well as the strain amplitude and frequencies of gravitational waves from their mergers, besides its many effects on structures of nuclei as well as the dynamics and observables of their collisions. Siemens (1970s) observed that $E_{\mathrm{sym}}(\rho)$ scales as $(\rho/\rho_0)^{2/3}$ near the saturation density $\rho_0$ of nuclear matter, since both the kinetic part and the potential contribution (quadratic in momentum) exhibit this dependence. The scaling holds if: (1) the nucleon isoscalar potential is quadratic in momentum, and (2) the isovector interaction is weakly density dependent. After examining many empirical evidences and understanding theoretical findings in the literature we conclude that: (1) Siemens' $\rho^{2/3}$ scaling is robust and serves as a valuable benchmark for both nuclear theories and experiments up to $2\rho_0$ but breaks down at higher densities, (2) Experimental and theoretical findings about $E_{\mathrm{sym}}(\rho)$ up to $2\rho_0$ are broadly consistent, but uncertainties remain large for its curvature $K_{\mathrm{sym}}$ and higher-order parameters, (3) Above $2\rho_0$, uncertainties grow due to poorly constrained spin-isospin dependent tensor and three-body forces as well as the resulting nucleon short-range correlations. Looking forward, combining multimessengers from both observations of neutron stars and terrestrial heavy-ion reaction experiments is the most promising path to finally constraining precisely the high-density $E_{\mathrm{sym}}(\rho)$ and the EOS of supradense neutron-rich matter.
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https://arxiv.org/abs/2510.05508
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Academic Papers
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2d782b8e69135cf4824470749ac4618783cf97b4b79f579e78deac1d044b4165
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2026-01-07T00:00:00-05:00
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Observable Signatures of a Quarkyonic Phase in Neutron Stars
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arXiv:2510.23405v2 Announce Type: replace-cross Abstract: Performing Bayesian inference on quarkyonic equation-of-state models for neutron star matter, we find they satisfy all current astrophysical observations, thus reinforcing the argument for the use of such neutron star matter equation-of-state models alongside traditional ones. To observationally differentiate between stars with and without a quarkyonic phase, we identify a novel observational signature- the slope of the mass-radius relation at some fixed mass in conjunction with the sound speed at the star's center. In this plane, we find quarkyonic stars in a region with high central sound speed and positive slope, that is distinct from purely nucleonic stars. High accuracy NS radii measurements facilitated by the next generation of detectors, coupled with ongoing studies of mapping astrophysical observables to microphysical properties like sound speed can be used for testing this signature. Our results indicate that a neutron star with these properties would be a strong evidence for existence of a quarkyonic phase or a similar crossover transition in its core.
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https://arxiv.org/abs/2510.23405
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Academic Papers
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c3a97d980c080f272b23f0c850a90974736b707ce61f6cca1777ab35e62bb11b
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2026-01-07T00:00:00-05:00
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On the Bondi accretion of a self-interacting complex scalar field
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arXiv:2511.04650v2 Announce Type: replace-cross Abstract: Scalar fields with a global U(1) symmetry often appear in cosmology and astrophysics. We study the spherically-symmetric, stationary accretion of such a classical field onto a Schwarzschild black hole in the test-field approximation. Thus, we consider the relativistic Bondi accretion beyond a simplified perfect-fluid setup. We focus on the complex scalar field with canonical kinetic term and with a generic quartic potential which either preserves the U(1) symmetry or exhibits spontaneous symmetry breaking. It is well known that in the lowest order in gradient expansion the dynamics of such a scalar field is well approximated by a perfect superfluid; we demonstrate that going beyond this approximation systematically reduces the accretion rate with respect to the perfect fluid case. Hence, black holes can provide a way to distinguish a perfect fluid from its ultraviolet completion in form of the complex scalar field.
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https://arxiv.org/abs/2511.04650
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Academic Papers
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1850e6f7c03e5fb67c0ee2f3fa4537726a3945aa88a6f52243b67036978ebc94
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2026-01-07T00:00:00-05:00
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Graviton-Photon Mixing by a Kerr-Newman Black Hole with Worldline EFT
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arXiv:2601.00980v2 Announce Type: replace-cross Abstract: In black hole perturbation theory, the difficulty in separating electromagnetic and gravitational sectors of the coupled Teukolsky equations has prevented a general treatment of scattering processes involving both electromagnetic waves and gravitational waves in presence of a Kerr-Newman black hole. We present the first computation of the gauge-invariant, low-frequency scattering amplitude for graviton photoproduction by a Kerr-Newman black hole at tree level up to $\mathcal{O}\big((\omega/m)^2\big)$ or $\mathcal{O}(S^2)$ and linear in $\kappa$, using the worldline effective field theory. The relevant Wilson coefficients are determined by matching the graviton and photon one-point functions to the Kerr-Newman solution. We obtain the full angular dependence of the conversion cross section in the presence of spin and comment on the factorization relation between the graviton photoproduction amplitude and the photon Compton amplitude for a classical spinning source. The result provides a benchmark for future analyses of coupled gravitoelectromagnetic scattering in spinning charged compact object backgrounds.
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https://arxiv.org/abs/2601.00980
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Academic Papers
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41db9fb3c4fedd42f6210fa229c566e0de04cdd967b380add7fe5b6dd26fa56f
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2026-01-07T00:00:00-05:00
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Improving Financial Forecasting with a Synergistic LLM-Transformer Architecture: A Hybrid Approach to Stock Price Prediction
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arXiv:2601.02878v1 Announce Type: new Abstract: This study proposes a novel hybrid deep learning framework that integrates a Large Language Model (LLM) with a Transformer architecture for stock price forecasting. The research addresses a critical theoretical gap in existing approaches that empirically combine textual and numerical data without a formal understanding of their interaction mechanisms. We conceptualise a prompt-based LLM as a mathematically defined signal generator, capable of extracting directional market sentiment and an associated confidence score from financial news. These signals are then dynamically fused with structured historical price features through a noise-robust gating mechanism, enabling the Transformer to adaptively weigh semantic and quantitative information. Empirical evaluations demonstrate that the proposed Hybrid LLM-Transformer model significantly outperforms a Vanilla Transformer baseline, reducing the Root Mean Squared Error (RMSE) by 5.28% (p = 0.003). Moreover, ablation and robustness analyses confirm the model's stability under noisy conditions and its capacity to maintain interpretability through confidence-weighted attention. The findings provide both theoretical and empirical support for a paradigm shift from empirical observation to formalised modelling of LLM-Transformer interactions, paving the way toward explainable, noise-resilient, and semantically enriched financial forecasting systems.
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https://arxiv.org/abs/2601.02878
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Academic Papers
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8c6ea382ebe8cbf5ba9417016c98753d68f82fc8797a54ac2df3c2bcb7c555ba
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2026-01-07T00:00:00-05:00
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Revealed Decision Rules in Choices Under Risk
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arXiv:2601.02964v1 Announce Type: new Abstract: We study decision making under risk when perception may be menu-dependent. Behavior is modeled as the outcome of a small library of psychologically interpretable, menu-specific rules that transform each objective menu into a perceived one. At each menu, the applied rule must make the realized choice a strict improvement under a dominance benchmark on perceived lotteries. We introduce the Maximum Rule Concentration Index (MRCI), the maximal Herfindahl-Hirschman concentration of rule shares over all locally admissible assignments, and diagnostics that distinguish rules that unify behavior across many menus from rules that mainly act as substitutes. We provide a MIQP formulation, a scalable heuristic, and a finite-sample permutation test of excess concentration relative to a menu-independent random-choice benchmark. Applied to the CPC18 dataset (N=686 subjects, each making 500-700 repeated binary lottery choices), the mean MRCI is 0.545, and 64.1% of subjects reject random choice at the 1% level. Concentration gains are primarily driven by modal-payoff focusing, salience-thinking, and regret-based comparisons.
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https://arxiv.org/abs/2601.02964
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5b91aa0baea8f204ec08a3ae24d68102d999ffd298a2f40ad1e2a791cc174271
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2026-01-07T00:00:00-05:00
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Volatility Spillovers in High-Dimensional Financial Systems: A Machine Learning Approach
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arXiv:2601.03146v1 Announce Type: new Abstract: We identify volatility spillovers across commodities, equities, and treasuries using a hybrid HAR-ElasticNet framework on daily realized volatility for six futures markets over 2002--2025. Our two step procedure estimates own-volatility dynamics via OLS to preserve persistence (roughly 0.99), then applies ElasticNet regularization to cross-market spillovers. The sparse network structure that emerges shows equity markets (ES, NQ) act as the primary volatility transmitters, while crude oil (CL) ends up being the largest receiver of cross-market shocks. Agricultural commodities stay isolated from the larger network. A simple univariate HAR model achieves equally performing point forecasts as our model, but our approach reveals network structure that univariate models cannot. Joint Impulse Response Functions trace how shocks propagate through the network. Our contribution is to demonstrate that hybrid estimation methods can identify meaningful spillover pathways while preserving forecast performance.
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https://arxiv.org/abs/2601.03146
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Academic Papers
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4deebf7261c2f55f99e46ad340c4f0abfb83fb9a563d0b73281f2068269be1ad
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2026-01-07T00:00:00-05:00
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Existence of Optimal Mechanisms for Selling Multiple Goods: An Elementary Proof
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arXiv:2601.01607v1 Announce Type: cross Abstract: We provide an elementary proof that revenue-maximizing mechanisms exist in multi-parameter settings whenever the distribution of valuations has finite expectation.
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https://arxiv.org/abs/2601.01607
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Academic Papers
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3fa65ed0730ca0110591f67ecf80d7fd51dcf7aa062e3b5fbf0973676f581905
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2026-01-07T00:00:00-05:00
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Sensitivity Analysis in Unconditional Quantile Effects
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arXiv:2303.14298v4 Announce Type: replace Abstract: This paper proposes a framework to analyze the effects of counterfactual policies on the unconditional quantiles of an outcome variable. For a given counterfactual policy, we obtain identified sets for the effect of both marginal and global changes in the proportion of treated individuals. To conduct a sensitivity analysis, we introduce the quantile breakdown frontier, a curve that (i) indicates whether a sensitivity analysis is possible or not, and (ii) when a sensitivity analysis is possible, quantifies the amount of selection bias consistent with a given conclusion of interest across different quantiles. To illustrate our method, we perform a sensitivity analysis on the effect of unionizing low income workers on the quantiles of the distribution of (log) wages.
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https://arxiv.org/abs/2303.14298
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Academic Papers
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61cfac01d651fe906145a529894685047c569bab4806bf313e7d401986883b2e
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2026-01-07T00:00:00-05:00
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Incentivizing Knowledge Transfers
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arXiv:2507.11018v2 Announce Type: replace Abstract: We study the optimal design of relational contracts that incentivize an expert to share specialized knowledge with a novice. While the expert fears that a more knowledgeable novice may later erode his future rents, a third-party principal is willing to allocate her resources to facilitate knowledge transfer. In the unique profit-maximizing contract between the principal and the expert, the expert is asked to train the novice as much as possible, for free, in the initial period; knowledge transfers then proceed gradually and perpetually, while the principal offers lump-sum compensations to the expert right after verifying each transfer; even in the long run, a complete knowledge transfer might not be attainable. Our analysis sheds light on the success of several prominent cross-border technology transfers that took place in China's auto industry and Korea's high-speed rail development.
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https://arxiv.org/abs/2507.11018
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Academic Papers
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74ea20b2d30d9025dcea453934ba4dcd2aae1ae872ac5a81196b6150d5c8ff87
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2026-01-07T00:00:00-05:00
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Cognitive biases shape the evolution of zero-sum norms
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arXiv:2511.16453v2 Announce Type: replace Abstract: Why do maladaptive perceptions and norms, such as zero-sum interpretations of interaction, persist even when they undermine cooperation and investment? We develop a framework where bounded rationality and heterogeneous cognitive biases shape the evolutionary dynamics of norm coordination. Extending evolutionary game theory with quantal response equilibria and prospect-theoretic utility, we show that subjective evaluation of payoffs systematically alters population-level equilibrium selection, generating stable but inefficient attractors. Counterintuitively, our analysis demonstrates that the benefit of rationality and the cost of risk aversion on welfare behave in nonmonotone ways: intermediate precision enhances coordination, while excessive precision or strong loss aversion leads to persistent lock-in at low-payoff and zero-sum equilibria. These dynamics produce an endogenous equity-efficiency trade-off: parameter configurations that raise aggregate welfare also increase inequality, while more equal distributions are associated with lower efficiency. The results highlight how distorted payoff perceptions can anchor societies in divergent institutional trajectories, offering a behavioral-evolutionary explanation for persistent zero-sum norms and inequality.
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https://arxiv.org/abs/2511.16453
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Academic Papers
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3a1ea7a4eb5f586645563874c3ab554a237865c5d74a9ea01e84e8cc407c1604
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2026-01-07T00:00:00-05:00
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Generalized method of moments with partially missing data
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arXiv:2511.21988v2 Announce Type: replace Abstract: We consider a generalized method of moments framework in which a part of the data vector is missing for some units in a completely unrestricted, potentially endogenous way. In this setup, the parameters of interest are usually only partially identified. We characterize the identified set for such parameters using the support function of the convex set of moment predictions consistent with the data. This identified set is sharp, valid for both continuous and discrete data, and straightforward to estimate. We also propose a statistic for testing hypotheses and constructing confidence regions for the true parameter, show that standard nonparametric bootstrap may not be valid, and suggest a fix using the bootstrap for directionally differentiable functionals of Fang and Santos (2019). A set of Monte Carlo simulations demonstrates that both our estimator and the confidence region perform well when samples are moderately large and the data have bounded supports.
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https://arxiv.org/abs/2511.21988
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Academic Papers
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d6221c9a011c1125c5f70df6692c06a69fdd7b11e50ba643b67bf2bc745b1985
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2026-01-07T00:00:00-05:00
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Improve Power of Knockoffs with Annotation Information of Covariates
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arXiv:2601.02583v1 Announce Type: new Abstract: Genome-wide association studies (GWAS) often find association signals between many genetic variants and traits of interest in a genomic region. Functional annotations of these variants provide valuable prior information that helps prioritize biologically relevant variants and enhances the power to detect causal variants. However, due to substantial correlations among these variants, a critical question is how to rigorously control the false discovery rate while effectively leveraging prior knowledge. We introduce annotation-informed knockoffs (AnnoKn), a knockoff-based method that performs annotation-informed variable selection with strict control of the false discovery rate. AnnoKn integrates the knockoff procedure with adaptive Lasso regression to evaluate the importance of multiple covariates while incorporating functional annotation information within a unified Bayesian framework. To facilitate real-world applications where individual-level data are not accessible, we further extend AnnoKn to operate on summary statistics. Through simulations and real-world applications to GTEx and GWAS datasets, we show that AnnoKn achieves superior power in detecting causal genetic variants compared with existing annotation-informed variable selection methods, while maintaining valid control over false discoveries.
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https://arxiv.org/abs/2601.02583
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Academic Papers
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0feba046e9c220ba34b1365d71b3b549987a962ab2d7d4027dde5959c8dbcff5
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2026-01-07T00:00:00-05:00
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Conformal novelty detection with false discovery rate control at the boundary
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arXiv:2601.02610v1 Announce Type: new Abstract: Conformal novelty detection is a classical machine learning task for which uncertainty quantification is essential for providing reliable results. Recent work has shown that the BH procedure applied to conformal p-values controls the false discovery rate (FDR). Unfortunately, the BH procedure can lead to over-optimistic assessments near the rejection threshold, with an increase of false discoveries at the margin as pointed out by Soloff et al. (2024). This issue is solved therein by the support line (SL) correction, which is proven to control the boundary false discovery rate (bFDR) in the independent, non-conformal setting. The present work extends the SL method to the conformal setting: first, we show that the SL procedure can violate the bFDR control in this specific setting. Second, we propose several alternatives that provably control the bFDR in the conformal setting. Finally, numerical experiments with both synthetic and real data support our theoretical findings and show the relevance of the new proposed procedures.
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https://arxiv.org/abs/2601.02610
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1271d938340cfdacd7a7977f7e6b156dde30179ee4182ac0cd4dec741d5a38a6
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2026-01-07T00:00:00-05:00
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Bayesian Multiple Multivariate Density-Density Regression
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arXiv:2601.02640v1 Announce Type: new Abstract: We propose the first approach for multiple multivariate density-density regression (MDDR), making it possible to consider the regression of a multivariate density-valued response on multiple multivariate density-valued predictors. The core idea is to define a fitted distribution using a sliced Wasserstein barycenter (SWB) of push-forwards of the predictors and to quantify deviations from the observed response using the sliced Wasserstein (SW) distance. Regression functions, which map predictors' supports to the response support, and barycenter weights are inferred within a generalized Bayes framework, enabling principled uncertainty quantification without requiring a fully specified likelihood. The inference process can be seen as an instance of an inverse SWB problem. We establish theoretical guarantees, including the stability of the SWB under perturbations of marginals and barycenter weights, sample complexity of the generalized likelihood, and posterior consistency. For practical inference, we introduce a differentiable approximation of the SWB and a smooth reparameterization to handle the simplex constraint on barycenter weights, allowing efficient gradient-based MCMC sampling. We demonstrate MDDR in an application to inference for population-scale single-cell data. Posterior analysis under the MDDR model in this example includes inference on communication between multiple source/sender cell types and a target/receiver cell type. The proposed approach provides accurate fits, reliable predictions, and interpretable posterior estimates of barycenter weights, which can be used to construct sparse cell-cell communication networks.
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https://arxiv.org/abs/2601.02640
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3aad809b885744ee0d6acac3d707c456209e22a836674bc64e818996415ad1e1
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2026-01-07T00:00:00-05:00
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Beyond Point Estimates: Toward Proper Statistical Inferencing and Reporting of Intraclass Correlation Coefficients
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arXiv:2601.02765v1 Announce Type: new Abstract: Reporting test-retest reliability using the intraclass correlation coefficient (ICC) has received increasing attention due to the criticisms of poor transparency and replicability in neuroimaging research, as well as many other biomedical studies. Numerous studies have thus evaluated the reliability of their findings by comparing ICCs, however, they often failed to test statistical differences between ICCs or report confidence intervals. Relying solely on point estimates may preclude valid inference about population-level differences and compromise the reliability of conclusions. To address this issue, this study systematically reviewed the use of ICC in articles published in NeuroImage from 2022 to 2024, highlighting the prevalence of misreporting and misuse of ICCs. We further provide practical guidelines for conducting appropriate statistical inference on ICCs. For practitioners in this area, we introduce an online application for statistical testing and sample size estimation when utilizing ICCs. We recalculated confidence intervals and formally tested ICC values reported in the reviewed articles, thereby reassessing the original inferences. Our results demonstrate that exclusive reliance on point estimates could lead to unreliable or even misleading conclusions. Specifically, only two of the eleven reviewed articles provided unequivocally valid statistical inferences based on ICCs, whereas two articles failed to yield any valid inference at all, raising serious concerns about the replicability of findings in this field. These results underscore the urgent need for rigorous inferential frameworks when reporting and interpreting ICCs.
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https://arxiv.org/abs/2601.02765
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831c3dc73f7ec71b9b22795af863d48b9d1a33abe00b9fca9e1f3c83ec603a88
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2026-01-07T00:00:00-05:00
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Scalable Ultra-High-Dimensional Quantile Regression with Genomic Applications
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arXiv:2601.02826v1 Announce Type: new Abstract: Modern datasets arising from social media, genomics, and biomedical informatics are often heterogeneous and (ultra) high-dimensional, creating substantial challenges for conventional modeling techniques. Quantile regression (QR) not only offers a flexible way to capture heterogeneous effects across the conditional distribution of an outcome, but also naturally produces prediction intervals that help quantify uncertainty in future predictions. However, classical QR methods can face serious memory and computational constraints in large-scale settings. These limitations motivate the use of parallel computing to maintain tractability. While extensive work has examined sample-splitting strategies in settings where the number of observations $n$ greatly exceeds the number of features $p$, the equally important (ultra) high-dimensional regime ($p >> n$) has been comparatively underexplored. To address this gap, we introduce a feature-splitting proximal point algorithm, FS-QRPPA, for penalized QR in high-dimensional regime. Leveraging recent developments in variational analysis, we establish a Q-linear convergence rate for FS-QRPPA and demonstrate its superior scalability in large-scale genomic applications from the UK Biobank relative to existing methods. Moreover, FS-QRPPA yields more accurate coefficient estimates and better coverage for prediction intervals than current approaches. We provide a parallel implementation in the R package fsQRPPA, making penalized QR tractable on large-scale datasets.
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https://arxiv.org/abs/2601.02826
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5406d906725fa89f6637a5ba102314ec0414210d8217f12b9e21c60ef0fffdfa
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2026-01-07T00:00:00-05:00
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Bayes Factor Group Sequential Designs
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arXiv:2601.02851v1 Announce Type: new Abstract: The Bayes factor, the data-based updating factor from prior to posterior odds, is a principled measure of relative evidence for two competing hypotheses. It is naturally suited to sequential data analysis in settings such as clinical trials and animal experiments, where early stopping for efficacy or futility is desirable. However, designing such studies is challenging because computing design characteristics, such as the probability of obtaining conclusive evidence or the expected sample size, typically requires computationally intensive Monte Carlo simulations, as no closed-form or efficient numerical methods exist. To address this issue, we extend results from classical group sequential design theory to sequential Bayes factor designs. The key idea is to derive Bayes factor stopping regions in terms of the z-statistic and use the known distribution of the cumulative z-statistics to compute stopping probabilities through multivariate normal integration. The resulting method is fast, accurate, and simulation-free. We illustrate it with examples from clinical trials, animal experiments, and psychological studies. We also provide an open-source implementation in the bfpwr R package. Our method makes exploring sequential Bayes factor designs as straightforward as classical group sequential designs, enabling experiments to rapidly design informative and efficient experiments.
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https://arxiv.org/abs/2601.02851
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ce6d8101fdfd8e148a813a52a14b65600e1b9d3bb946b36e0526d3836fa205f4
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2026-01-07T00:00:00-05:00
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On the bias of the Hoover index estimator: Results for the gamma distribution
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arXiv:2601.03059v1 Announce Type: new Abstract: The Hoover index is a widely used measure of inequality with an intuitive interpretation, yet little is known about the finite-sample properties of its empirical estimator. In this paper, we derive a simple expression for the expected value of the Hoover index estimator for general non-negative populations, based on Laplace transform techniques and exponential tilting. This unified framework applies to both continuous and discrete distributions. Explicit bias expressions are obtained for gamma population, showing that the estimator is generally biased in finite samples. Numerical and simulation results illustrate the magnitude of the bias and its dependence on the underlying distribution and sample size.
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https://arxiv.org/abs/2601.03059
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d449ccfd2f6bdeb2edc360390fe5b0cadfc474f6b3605fa4d823b339e1475db9
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2026-01-07T00:00:00-05:00
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A non-parametric approach for estimating the correlation between log-rank test statistics with applications to a conjunctive power calculation
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arXiv:2601.03069v1 Announce Type: new Abstract: We present a method for estimating the correlation between log-rank test statistics evaluating separate null hypotheses for two time-to-event endpoints. The correlation is estimated using subject-level data by a non-parametric approach based on the independent and identically distributed (iid) decomposition of the log-rank test statistic under any alternative. Using the iid decomposition, we are able to make an assumption-lean estimation of the correlation. A motivating example using the developed approach is provided. Here, we illustrate how the suggested approach can be used to give a realistic quantification of expected conjunctive power that can guide the design of a new randomized clinical trial using historical data. Finally, we investigate the method's finite sample properties via a simulation study that confirms unbiased and consistent behavior of the proposed approach. In addition, the simulation study gives insight into the effects of censoring on the correlation between the log-rank test statistics.
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https://arxiv.org/abs/2601.03069
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Academic Papers
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1a01c827798db39c0b58aa2e7da3b843ad65419991fd12bbf201b425ed173ea2
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2026-01-07T00:00:00-05:00
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Bayesian score calibration for approximate models
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arXiv:2211.05357v5 Announce Type: replace Abstract: Scientists continue to develop increasingly complex mechanistic models to reflect their knowledge more realistically. Statistical inference using these models can be challenging since the corresponding likelihood function is often intractable and model simulation may be computationally burdensome. Fortunately, in many of these situations it is possible to adopt a surrogate model or approximate likelihood function. It may be convenient to conduct Bayesian inference directly with a surrogate, but this can result in a posterior with poor uncertainty quantification. In this paper, we propose a new method for adjusting approximate posterior samples to reduce bias and improve posterior coverage properties. We do this by optimizing a transformation of the approximate posterior, the result of which maximizes a scoring rule. Our approach requires only a (fixed) small number of complex model simulations and is numerically stable. We develop supporting theory for our method and demonstrate beneficial corrections to approximate posteriors across several examples of increasing complexity.
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https://arxiv.org/abs/2211.05357
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3ca403a8f8c4390c89ab984944d13b94f7d1397d32a5df46bedad54f11a2aa83
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2026-01-07T00:00:00-05:00
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Scalable Bayesian Inference for Generalized Linear Mixed Models via Stochastic Gradient MCMC
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arXiv:2403.03007v3 Announce Type: replace Abstract: The generalized linear mixed model (GLMM) is widely used for analyzing correlated data, particularly in large-scale biomedical and social science applications. Scalable Bayesian inference for GLMMs is challenging because the marginal likelihood is intractable and conventional Markov chain Monte Carlo (MCMC) methods become computationally prohibitive as the number of subjects grows. We develop a stochastic gradient MCMC (SGMCMC) algorithm tailored to GLMMs that enables accurate posterior inference in the large-sample regime. Our approach uses Fisher's identity to construct an unbiased Monte Carlo estimator of the gradient of the marginal log-likelihood, making SGMCMC feasible when direct gradient computation is impossible. We analyze the additional variability introduced by both minibatching and gradient approximation, and derive a post-hoc covariance correction that yields properly calibrated posterior uncertainty. Through simulations, we show that the proposed method provides accurate posterior means and variances, outperforming existing approaches, including control variate methods, in large-$n$ settings. We further demonstrate the method's practical utility in an analysis of electronic health records data, where accounting for variance inflation materially changes scientific conclusions.
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https://arxiv.org/abs/2403.03007
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290e042a42950f163007012ab3fa028ac8b49425627ec805d48f64f3d94a9f4f
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2026-01-07T00:00:00-05:00
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Scalable magnetic resonance fingerprinting: Incremental inference of high dimensional elliptical mixtures from large data volumes
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arXiv:2412.10173v2 Announce Type: replace Abstract: Magnetic Resonance Fingerprinting (MRF) is an emerging technology with the potential to revolutionize radiology and medical diagnostics. In comparison to traditional magnetic resonance imaging (MRI), MRF enables the rapid, simultaneous, non-invasive acquisition and reconstruction of multiple tissue parameters, paving the way for novel diagnostic techniques. In the original matching approach, reconstruction is based on the search for the best matches between in vivo acquired signals and a dictionary of high-dimensional simulated signals (fingerprints) with known tissue properties. A critical and limiting challenge is that the size of the simulated dictionary increases exponentially with the number of parameters, leading to an extremely costly subsequent matching. In this work, we propose to address this scalability issue by considering probabilistic mixtures of high-dimensional elliptical distributions, to learn more efficient dictionary representations. Mixture components are modelled as flexible ellipitic shapes in low dimensional subspaces. They are exploited to cluster similar signals and reduce their dimension locally cluster-wise to limit information loss. To estimate such a mixture model, we provide a new incremental algorithm capable of handling large numbers of signals, allowing us to go far beyond the hardware limitations encountered by standard implementations. We demonstrate, on simulated and real data, that our method effectively manages large volumes of MRF data with maintained accuracy. It offers a more efficient solution for accurate tissue characterization and significantly reduces the computational burden, making the clinical application of MRF more practical and accessible.
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https://arxiv.org/abs/2412.10173
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906bfd34b5207ec89d1c9daf3203eb315fe0fa56037d26efb8510674cf41a952
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2026-01-07T00:00:00-05:00
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Successive classification learning for estimating quantile optimal treatment regimes
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arXiv:2507.11255v2 Announce Type: replace Abstract: Quantile optimal treatment regimes (OTRs) aim to assign treatments that maximize a specified quantile of patients' outcomes. Compared to treatment regimes that target the mean outcomes, quantile OTRs offer fairer regimes when a lower quantile is selected, as it improves outcomes for vulnerable patients. In this paper, we propose a novel method for estimating quantile OTRs by reformulating the problem as a successive classification task, solvable via training a sequence of classifiers, each successive classifier built on the output of its predecessors. This reformulation enables us to leverage the powerful machine learning technique to enhance computational efficiency and handle complex decision boundaries. We also investigate the estimation of quantile OTRs when outcomes are discrete, a setting that has received limited attention in the literature. A key challenge is that direct extensions of existing methods to discrete outcomes often lead to inconsistency and ineffectiveness issues. To overcome this, we introduce a smoothing technique that maps discrete outcomes to continuous surrogates, enabling consistent and effective estimation. We provide theoretical guarantees to support our methodology, and demonstrate its superior performance through comprehensive simulation studies and real-data analysis.
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https://arxiv.org/abs/2507.11255
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84a4daf48966ebdedcb9903b43f4db2e652bb2a3e1b0bb71ea19863f385cd29b
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2026-01-07T00:00:00-05:00
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Causal Judge Evaluation: Calibrated Surrogate Metrics for LLM Systems
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arXiv:2512.11150v2 Announce Type: replace Abstract: Measuring long-run LLM outcomes (user satisfaction, expert judgment, downstream KPIs) is expensive. Teams default to cheap LLM judges, but uncalibrated proxies can invert rankings entirely. Causal Judge Evaluation (CJE) makes it affordable to aim at the right target: calibrate cheap scores against 5% oracle labels, then evaluate at scale with valid uncertainty. On 4,961 Arena prompts, CJE achieves 99% ranking accuracy at 14x lower cost. Key findings: naive confidence intervals on uncalibrated scores achieve 0% coverage (CJE: ~95%); importance-weighted estimators fail despite 90%+ effective sample size. We introduce the Coverage-Limited Efficiency (CLE) diagnostic explaining why. CJE combines mean-preserving calibration (AutoCal-R), weight stabilization (SIMCal-W), and bootstrap inference that propagates calibration uncertainty (OUA), grounded in semiparametric efficiency theory.
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https://arxiv.org/abs/2512.11150
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ea43e4457132554056e38f4356e30aa3e0f734365a33af1fc14b6959da2eb3f7
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2026-01-07T00:00:00-05:00
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Minimal length: a source of non-Hermiticity and non-locality in quantum mechanics
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arXiv:2601.02413v1 Announce Type: new Abstract: First, the study tries to shed light on the relationship between purely quantum mechanical momentum measurements (canonical momentum space) and measurements of the generalized momentum operator, including minimal length effects. Additionally, the existence of complex numbers in quantum mechanics seems justifiable as a consequence of minimal length. Finally, a novel method for generating quantum entangled states with complex quantum numbers inspired by the minimal length is also reported. Therefore, theories including a minimal length, like some quantum scenarios of gravity, seem to be able to enrich the current understanding of non-locality.
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https://arxiv.org/abs/2601.02413
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91e63a63bbfa4453046702c0b7b373e483fef16298b0296acbc9367b959c9e64
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2026-01-07T00:00:00-05:00
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Gravitational time dilation in quantum clock interferometry with entangled multi-photon states and quantum memories
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arXiv:2601.02470v1 Announce Type: new Abstract: Gravitational time dilation implies that clocks held at different heights accumulate different proper times. We analyze a memory-assisted quantum clock interferometer in which a frequency-bin photonic clock is stored in two vertically separated quantum memories for a controllable duration, such that the joint state evolves in a quantum superposition of two proper times. After retrieval, the photonic modes interfere in a Hong-Ou-Mandel (HOM) interferometer, for which we derive analytic expressions for the resulting multiphoton detection statistics. Extending this HOM-based scheme from entangled photon pairs to frequency-entangled 2N-photon inputs, we show that the proper-time dependent phase is amplified by a factor N, leading to an N-times faster collapse and revival of the interference signal compared with the two-photon case. Incorporating finite memory efficiency and lifetime, we identify regimes where this modulation remains observable. For parameters compatible with demonstrated Rb and Cs memories and achievable optical frequency separations, the first collapse occurs for height differences in the order of 10-100 m with subsecond to few-second storage times, while suitable rare-earth ion and alkali memory combinations can reduce the required height to the few-metre scale. These results establish near-term laboratory conditions for observing entanglement dynamics driven by gravitational time dilation in a photonic platform.
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https://arxiv.org/abs/2601.02470
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7886230d607dd32982455a0d4b5ff3792f4c1d2a507d6e78f9c471b344c96cd5
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2026-01-07T00:00:00-05:00
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Gaussian time-translation covariant operations: structure, implementation, and thermodynamics
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arXiv:2601.02471v1 Announce Type: new Abstract: Time-translation symmetry strongly constrains physical dynamics, yet systematic characterization for continuous-variable systems lags behind its discrete-variable counterpart. We close this gap by providing a rigorous classification of Gaussian quantum operations that are covariant under time translations, termed Gaussian covariant operations. We show that several key results known for discrete-variable covariant operations break down in the Gaussian optical setting: discrepancies arise in physical and thermodynamic implementation, in the extensivity of asymmetry, and in catalytic advantages. Our results provide comprehensive mathematical and operational toolkits for Gaussian covariant operations, including a peculiar pair of asymmetry measures that are completely non-extensive. Our findings also reveal surprising consequences of the interplay among symmetry, Gaussianity, and thermodynamic constraints, suggesting that real-world scenarios with multiple constraints have a rich structure not accessible from examining individual constraints separately.
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https://arxiv.org/abs/2601.02471
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131cd1a23b2a7326172c1fc5b7bbade23559df66554813b1e7f6c072fe448a6a
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2026-01-07T00:00:00-05:00
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Minimization of AND-XOR Expressions with Decoders for Quantum Circuits
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arXiv:2601.02515v1 Announce Type: new Abstract: This paper introduces a new logic structure for reversible quantum circuit synthesis. Our synthesis method aims to minimize the quantum cost of reversible quantum circuits with decoders. In this method, multi-valued input, binary output (MVI) functions are utilized as a mathematical concept only, but the circuits are binary. We introduce the new concept of ``Multi-Valued Input Fixed Polarity Reed-Muller (MVI-RM)" forms. Our decoder-based circuit uses three logical levels in contrast to commonly-used methods based on Exclusive-or Sum of Products (ESOP) with two levels (AND-XOR expressions), realized by Toffoli gates. In general, the high number of input qubits in the resulting Toffoli gates is a problem that greatly impacts the quantum cost. Using decoders decreases the number of input qubits in these Toffoli gates. We present two practical algorithms for three-level circuit synthesis by finding the MVI-FPRM: products-matching and the newly developed butterfly diagrams. The best MVI-FPRM forms are factorized and reduced to approximate Multi-Valued Input Generalized Reed-Muller (MVI-GRM) forms.
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https://arxiv.org/abs/2601.02515
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0394a2ec519d5da4e9a0ec9637411415d96408eeaa4f92a43a2f0662f7a28109
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2026-01-07T00:00:00-05:00
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Further Improving the Decoy State Quantum Key Distribution Protocol with Advantage Distillation
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arXiv:2601.02565v1 Announce Type: new Abstract: In this paper, we revisit the application of classical advantage distillation (CAD) to the decoy-state BB84 protocol. Prior work has shown that CAD can greatly improve maximal distances and noise tolerances of the practical decoy state protocol. However, past work in deriving key-rate bounds for this protocol with CAD have assumed a trivial bound on the quantum entropy, whenever Alice sends a vacuum state in a CAD block (i.e., the entropy of such blocks is taken to be zero). Since such rounds contribute, negatively, to the error correction leakage, this results in a correct, though sub-optimal bound. Here, we derive a new proof of security for CAD applied to the decoy state BB84 protocol, computing a bound on Eve's uncertainty in all possible single and vacuum photon events. We use this to derive a new asymptotic key-rate bound which, we show, outperforms prior work, allowing for increased distances and noise tolerances.
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https://arxiv.org/abs/2601.02565
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d07d93bee66651b3cb9bdf33e6659e125246b119605481db734b0b573b1b5a60
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2026-01-07T00:00:00-05:00
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Localization of joint quantum measurements on $\mathbb{C}^d \otimes \mathbb{C}^d$ by entangled resources with Schmidt number at most $d$
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arXiv:2601.02660v1 Announce Type: new Abstract: Localizable measurements are joint quantum measurements that can be implemented using only non-adaptive local operations and shared entanglement. We provide a protocol-independent characterization of localizable projection-valued measures (PVMs) by exploiting algebraic structures that any such measurement must satisfy. We first show that a rank-1 PVM on $\mathbb{C}^d\otimes\mathbb{C}^d$ containing an element with the maximal Schmidt rank can be localized using entanglement of a Schmidt number at most $d$ if and only if it forms a maximally entangled basis corresponding to a nice unitary error basis. This reveals strong limitations imposed by non-adaptive local operations, in contrast to the adaptive setting where any joint measurement is implementable. We then completely characterize two-qubit rank-1 PVMs that can be localized with two-qubit entanglement, resolving a conjecture of Gisin and Del Santo, and finally extend our characterization to ideal two-qudit measurements, strengthening earlier results.
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https://arxiv.org/abs/2601.02660
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ba2ecb641ec2b90adec442537dc87866591730a7d79692aac68c5b27f72e5c01
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2026-01-07T00:00:00-05:00
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Multiparameter quantum estimation with a uniformly accelerated Unruh-DeWitt detector
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arXiv:2601.02689v1 Announce Type: new Abstract: The uniformly accelerated Unruh-DeWitt detector serves as a fundamental model in relativistic quantum metrology. While previous studies have mainly concentrated on single-parameter estimation via quantum Cram\'er-Rao bound, the multi-parameter case remains significantly underexplored. In this paper, we investigate the multiparameter estimation for a uniformly accelerated Unruh-DeWitt detector coupled to a vacuum scalar field in both bounded and unbounded Minkowski vacuum. Our analysis reveals that quantum Cram\'er-Rao bound fails to provide a tight error bound for the two-parameter estimation involving the initial phase and weight parameters. For this reason, we numerically compute two tighter error bounds, Holevo Cram\'er-Rao bound and Nagaoka bound, based on a semidefinite program. Notably, our results demonstrate that Nagaoka bound yields the tightest error bound among all the considered error bounds, consistent with the general hierarchy of multiparameter quantum estimation. In the case with a boundary, we observe the introduction of boundary systematically reduces the values of both Holevo Cram\'er-Rao bound and Nagaoka bound, indicating an improvement on the attainable estimation precision. These results offer valuable insights on and practical guidance for advancing multiparameter estimation in relativistic context.
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https://arxiv.org/abs/2601.02689
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1918e730856d60b33ac53c6040ad5435ad808d59e9ca05d09d98c191a0d0e7ef
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2026-01-07T00:00:00-05:00
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Q-based, objective-field model for wave-function collapse: Analyzing measurement on a macroscopic superposition state
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arXiv:2601.02767v1 Announce Type: new Abstract: The measurement problem remains unaddressed in modern physics, with an array of proposed solutions but as of yet no agreed resolution. In this paper, we examine measurement using the Q-based, objective-field model for quantum mechanics. Schrodinger considered a microscopic system prepared in a superposition of states which is then coupled to a macroscopic meter. We analyze the entangled meter and system, and measurements on it, by solving forward-backward stochastic differential equations for real amplitudes $x(t)$ and $p(t)$ that correspond to the phase-space variables of the Q function of the system at a time $t$. We model the system and meter as single-mode fields, and measurement of $\hat{x}$ by amplification of the amplitude $x(t)$. Our conclusion is that the outcome for the measurement is determined at (or by) the time $t_{m}$, when the coupling to the meter is complete, the meter states being macroscopically distinguishable. There is consistency with macroscopic realism. By evaluating the distribution of the amplitudes $x$ and $p$ postselected on a given outcome of the meter, we show how the $Q$-based model represents a more complete description of quantum mechanics: The variances associated with amplitudes $x$ and $p$ are too narrow to comply with the uncertainty principle, ruling out that the distribution represents a quantum state. We conclude that the collapse of the wavefunction occurs as a two-stage process: First there is an amplification that creates branches of amplitudes $x(t)$ of the meter, associated with distinct eigenvalues. The outcome of measurement is determined by $x(t)$ once amplified, explaining Born's rule. Second, the distribution that determines the final collapse is the state inferred for the system conditioned on the outcome of the meter: information is lost about the meter, in particular, about the complementary variable $p$.
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https://arxiv.org/abs/2601.02767
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c14c12e02b4f3e8c0ec5cd9530ea8f9e1cdea45276bc208b209199b1faf8b232
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2026-01-07T00:00:00-05:00
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Quantum key distribution without authentication and information leakage
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arXiv:2601.02846v1 Announce Type: new Abstract: Quantum key distribution (QKD) is the most widely studied quantum cryptographic model that exploits quantum effects to achieve information-theoretically secure key establishment. Conventional QKD contains public classical post-processing steps that require authentication to prevent impersonation and maintain security. However, a major limitation of QKD is it cannot perform authentication by itself, and thus requires a separate authentication mechanism. In addition, these public classical steps also have information leakage which subjects QKD to additional attack strategies and reduces the final key rate. In this work, we propose a new QKD variant that removes the need for a separate authentication mechanism, eliminates information leakage, and achieves a substantially higher key rate. By having two more protocol keys than conventional QKD and no public classical steps, our design achieves (almost) perfect information-theoretic security with the protocol keys reusable.
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https://arxiv.org/abs/2601.02846
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c51609567c1358e09190a305788f042c75ac535ffe749a435e775c9680fb0bf7
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2026-01-07T00:00:00-05:00
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Entanglement Entropy for Screened Interactions via Dimensional Mapping to Harmonic Oscillators
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arXiv:2601.02877v1 Announce Type: new Abstract: We investigate interaction-induced corrections to entanglement entropy by mapping a screened Yukawa-type interaction to an effective harmonic oscillator system with controlled anharmonic perturbations. Starting from a one-dimensional interaction $V(x) = -g^2 e^{-\alpha m x}/x$, we reformulate the problem in terms of a four-dimensional radial oscillator, where the finite screening length generates a systematic hierarchy of polynomial interactions in the radial coordinate. This mapping enables a controlled Rayleigh-Schrodinger perturbative treatment of the ground-state wavefunction and an explicit spectral analysis of the reduced density matrix. Working in the weak-screening regime, we compute the leading non-Gaussian correction arising from the quartic interaction $\rho^4$, which appears at order $\alpha^2$ in the expansion of the Yukawa-like potential. We obtain closed analytic expressions for the resulting small eigenvalues of the reduced density matrix and evaluate their contribution to the von Neumann entanglement entropy. We show that the entropy receives analytic corrections at order $\alpha^2$, originating both from explicit anharmonic state-mixing effects and from the implicit $\alpha$ dependence of the Gaussian width parameter. Our results clarify the distinct roles of harmonic renormalization and genuinely non-Gaussian interactions in generating entanglement, establish a systematic power-counting and normalization scheme for higher-order $\rho^{2n}$ perturbations, and provide a transparent oscillator-based framework for computing entanglement entropy in weakly interacting low-dimensional and field-theoretic systems.
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https://arxiv.org/abs/2601.02877
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1e2e6ad77eefe95c0fd0854d4e29103e7f2b939056b8551e497e3b993f2ff868
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2026-01-07T00:00:00-05:00
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Trading symmetry for Hilbert-space dimension in Bell-inequality violation
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arXiv:2601.02893v1 Announce Type: new Abstract: In quantum information, asymmetry, i.e., the lack of symmetry, is a resource allowing one to accomplish certain tasks that are otherwise impossible. Similarly, in a Bell test using any given Bell inequality, the maximum violation achievable using quantum strategies respecting or disregarding a certain symmetry can be different. In this work, we focus on the symmetry involved in the exchange of parties and explore when we have to trade this symmetry for a lower-dimensional quantum strategy in achieving the maximal violation of given Bell inequalities. For the family of symmetric Collins-Gisin-Linden-Massar-Popescu inequalities, we provide evidence showing that there is no such trade-off. However, for several other Bell inequalities with a small number of dichotomic measurement settings, we show that symmetric quantum strategies in the minimal Hilbert space dimension can only lead to a suboptimal Bell violation. In other words, there exist symmetric Bell inequalities that can only be maximally violated by asymmetric quantum strategies of minimal dimension. In contrast, one can also find examples of asymmetric Bell inequalities that are maximally violated by symmetric correlations. The implications of these findings on the geometry of the set of quantum correlations and the possibility of performing self-testing therefrom are briefly discussed.
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https://arxiv.org/abs/2601.02893
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1d54e28efbbe3e4086ee18eb70be5b9c59ff6c0664e7253cb645b426eed9dcb9
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2026-01-07T00:00:00-05:00
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Violation of Bell Monogamy Relations
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arXiv:2601.02925v1 Announce Type: new Abstract: The entangled multipartite systems, specially in pure states, exhibit the phenomenon entanglement monogamy. Such systems also display the phenomenon of Bell nonlocality. Like entanglement monogamy relations, there are Bell monogamy relations. These relations suggest a sharing of nonlocality across the subsystems. The nonlocality, as characterized by Bell inequalities, of one subsystem limits the nonlocality exhibited by another subsystem. We show that the Bell monogamy relations can be violated by using local filtering operations. We consider permutation-symmetric multipartite pure states, in particular $W$ states, to demonstrate the violation.
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https://arxiv.org/abs/2601.02925
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30653354d2f7b7a8baa52d2e5c5e81e513fbb52bb90893ee486038931d247b1b
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2026-01-07T00:00:00-05:00
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Entanglement signatures of quantum criticality in Floquet non-Hermitian topological systems
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arXiv:2601.03002v1 Announce Type: new Abstract: The entanglement entropy can be an effective diagnostic tool for probing topological phase transitions. In one-dimensional single particle systems, the periodic driving generates a variety of topological phases and edge modes. In this work, we investigate the topological phase transition of the one-dimensional Floquet Su-Schrieffer-Heeger model using entanglement entropy, and construct the phase diagram based on entanglement entropy. The entanglement entropy exhibits pronounced peaks and follows the logarithmic scaling law at the phase transition points, from which we extract the central charge $c=1$. We further investigate the entanglement spectrum to accurately distinguish the different topological phases. In addition, the coupling between zero and $\pi$ modes leads to characteristic splittings in the entanglement spectrum, signaling their hybridization under periodic driving. These results remain robust in non-Hermitian regimes and in the presence of next-nearest-neighbor hopping, demonstrating the reliability and universality of entanglement entropy as a diagnostic for topological phase transitions.
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https://arxiv.org/abs/2601.03002
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6d43620dbf6ce30e361ae3a00be3186af6343c502564958b16144ea1a2bd7da3
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2026-01-07T00:00:00-05:00
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Who can compete with quantum computers? Lecture notes on quantum inspired tensor networks computational techniques
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arXiv:2601.03035v1 Announce Type: new Abstract: This is a set of lectures on tensor networks with a strong emphasis on the core algorithms involving Matrix Product States (MPS) and Matrix Product Operators (MPO). Compared to other presentations, particular care has been given to disentangle aspects of tensor networks from the quantum many-body problem: MPO/MPS algorithms are presented as a way to deal with linear algebra on extremely (exponentially) large matrices and vectors, regardless of any particular application. The lectures include well-known algorithms to find eigenvectors of MPOs (the celebrated DMRG), solve linear problems, and recent learning algorithms that allow one to map a known function into an MPS (the Tensor Cross Interpolation, or TCI, algorithm). The lectures end with a discussion of how to represent functions and perform calculus with tensor networks using the "quantics" representation. They include the detailed analytical construction of important MPOs such as those for differentiation, indefinite integration, convolution, and the quantum Fourier transform. Three concrete applications are discussed in detail: the simulation of a quantum computer (either exactly or with compression), the simulation of a quantum annealer, and techniques to solve partial differential equations (e.g. Poisson, diffusion, or Gross-Pitaevskii) within the "quantics" representation. The lectures have been designed to be accessible to a first-year PhD student and include detailed proofs of all statements.
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https://arxiv.org/abs/2601.03035
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2785286805cebc3c7ea429bffd5b42129519c65abe65ad5664d0811f7374a012
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2026-01-07T00:00:00-05:00
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Collective dynamics versus entanglement in quantum battery performance
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arXiv:2601.03119v1 Announce Type: new Abstract: Identifying the physical origin of enhanced charging performance in many-body quantum batteries is a key challenge in quantum thermodynamics. We investigate whether improvements in stored energy and instantaneous charging power arise from genuine quantum correlations or from coherent collective dynamics that are not intrinsically quantum. We compare the time evolution of energetic quantities with a hierarchy of information-theoretic measures probing bipartite, tripartite, and further-partite correlations. Across different battery charger configurations, we find a consistent temporal ordering in which the instantaneous power peaks before the buildup of strong quantum correlations, indicating that peak charging is dominated by coherent transport, while entanglement and scrambling develop at later times. Furthermore, charging protocols based on k local interactions are examined under both unconstrained and norm-constrained (fair) settings, enabling a clear distinction between classical scaling effects and genuine collective enhancements. Increasing the interaction order or the participation number does not automatically translate into higher charging power. Instead, the performance is primarily dictated by how many particles actually become mutually correlated and contribute to entanglement. Fully collective interactions provide a genuine advantage because all particles participate coherently, whereas partially extended interaction schemes fail to monotonically increase the number of effectively interacting particles, and therefore do not guarantee improved charging efficiency.
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https://arxiv.org/abs/2601.03119
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6a7ccc7dca7eea3607b8be5002479079c117cd8f74afbf678c3d7af9fa059a0b
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2026-01-07T00:00:00-05:00
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Operational modes of a Raman-coupled two-qubit quantum thermal machine
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arXiv:2601.03139v1 Announce Type: new Abstract: We investigate a quantum thermal machine composed of two qubits coupled through a Raman-induced exchange interaction and driven by inhomogeneous transition frequencies. The system is analyzed within Carnot, Otto, and Stirling thermodynamic cycles, including the Stirling cycle with and without regeneration. We identify the conditions under which the device operates as a heat engine, refrigerator, thermal accelerator, or heater. Efficiency maps and operational-mode diagrams reveal well-defined boundaries in parameter space, governed by the frequency ratio $r=\bar{\omega}/\omega$, the coupling strength $g$, and the thermal gradient between reservoirs. The Carnot cycle exhibits sharp transitions between engine and refrigerator regimes, while the Otto cycle displays a richer structure with the coexistence of all operational modes. The Stirling cycle shows enhanced versatility and performance, particularly when assisted by a regenerator, where near-ideal efficiencies are achieved. Overall, the Raman-type interaction introduces a controllable left-right asymmetry that enables nontrivial manipulation of thermodynamic behavior through frequency tuning.
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https://arxiv.org/abs/2601.03139
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9248503f2f8ac6ea1ca5371935c47c95eaa20cdb93ce4a7e67e8ffbe38ddb041
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2026-01-07T00:00:00-05:00
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Energetics of Rydberg-atom Quantum Computing
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arXiv:2601.03141v1 Announce Type: new Abstract: Quantum computing exploits the properties of Quantum Mechanics to solve problems faster than classical computers. The potential applications of this technology have been widely explored, and extensive research over the past decades has been dedicated to developing scalable quantum computers. However, the question of the energetic performance of quantum computation has only gained attention more recently, and its importance is now recognized. In fact, quantum computers can only be a viable alternative if their energy cost scales favorably, and some research has shown that there is even a potential quantum energy advantage. Rydberg atoms have emerged recently as one of the most promising platforms to implement a large-scale quantum computer, with significant advances made in recent years. This work aims at contributing first steps to understand the energy efficiency of this platform, namely by investigating the energy consumption of the different elements of a Rydberg atom quantum computer. First, an experimental implementation of the Quantum Phase Estimation algorithm is analyzed, and an estimation of the energetic cost of executing this algorithm is calculated. Then, a potential scaling of the energy cost of performing the Quantum Fourier Transform with Rydberg atoms is derived. This analysis facilitates a comparison of the energy consumption of different elements within a Rydberg atom quantum computer, from the preparation of the atoms to the execution of the algorithm, and the measurement of the final state, enabling the evaluation of the energy expenditure of the Rydberg platform and the identification of potential improvements. Finally, we used the Quantum Fourier Transform as an energetic benchmark, comparing the scaling we obtained to that of the execution of the Discrete Fourier Transform in two state-of-the-art classical supercomputers.
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https://arxiv.org/abs/2601.03141
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3aa355db36886c804fde7d343f9ff9b709660bd5968d8b29ef1c1a739b675cd4
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2026-01-07T00:00:00-05:00
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A Unified Frequency Principle for Quantum and Classical Machine Learning
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arXiv:2601.03169v1 Announce Type: new Abstract: Quantum neural networks constitute a key class of near-term quantum learning models, yet their training dynamics remain not fully understood. Here, we present a unified theoretical framework for the frequency principle (F-principle) that characterizes the training dynamics of both classical and quantum neural networks. Within this framework, we prove that quantum neural networks exhibit a spectral bias toward learning low-frequency components of target functions, mirroring the behavior observed in classical deep networks. We further analyze the impact of noise and show that, when single-qubit noise is applied after encoding-layer rotations and modeled as a Pauli channel aligned with the rotation axis, the Fourier component labeled by $\boldsymbol{\omega}$ is suppressed by a factor $(1-2\gamma)^{\|\boldsymbol{\omega}\|_1}$. This leads to exponential attenuation of high-frequency terms while preserving the learnability of low-frequency structure. In the same setting, we establish that the resulting noisy circuits admit efficient classical simulation up to average-case error. Numerical experiments corroborate our theoretical predictions: Quantum neural networks primarily learn low-frequency features during early optimization and maintain robustness against dephasing and depolarizing noise acting on the encoding layer. Our results provide a frequency-domain lens that unifies classical and quantum learning dynamics, clarifies the role of noise in shaping trainability, and guides the design of noise-resilient quantum neural networks.
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https://arxiv.org/abs/2601.03169
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cd56dad267efb8438fb8414c93919dc9ed1454c6abf45efe337c43758aead651
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2026-01-07T00:00:00-05:00
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FTCircuitBench: A Benchmark Suite for Fault-Tolerant Quantum Compilation and Architecture
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arXiv:2601.03185v1 Announce Type: new Abstract: Realizing large-scale quantum advantage is expected to require quantum error correction (QEC), making the compilation and optimization of logical operations a critical area of research. Logical computation imposes distinct constraints and operational paradigms that differ from those of the Noisy Intermediate-Scale Quantum (NISQ) regime, motivating the continued evolution of compilation tools. Given the complexity of this emerging stack, where factors such as gate decomposition precision and computational models must be co-designed, standardized benchmarks and toolkits are valuable for evaluating progress. To support this need, we introduce FTCircuitBench, which serves as: (1) a benchmark suite of impactful quantum algorithms, featuring pre-compiled instances in both Clifford+T and Pauli Based Computation models; (2) a modular end-to-end pipeline allowing users to compile and decompose algorithms for various fault-tolerant architectures, supporting both prebuilt and custom optimization passes; and (3) a toolkit for evaluating the impact of algorithms and optimization across the full compilation stack, providing detailed numerical analysis at each stage. FTCircuitBench is fully open-sourced and maintained on Github.
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https://arxiv.org/abs/2601.03185
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412ccccd5a172205393fc4c7fdf90ffadcc8fddc4e0bd6ac550f43b44c8d96b9
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2026-01-07T00:00:00-05:00
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Grand-Canonical Typicality
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arXiv:2601.03253v1 Announce Type: new Abstract: We study how the grand-canonical density matrix arises in macroscopic quantum systems. ``Canonical typicality'' is the known statement that for a typical wave function $\Psi$ from a micro-canonical energy shell of a quantum system $S$ weakly coupled to a large but finite quantum system $B$, the reduced density matrix $\hat{\rho}^S_\Psi=\mathrm{tr}^B |\Psi\rangle\langle \Psi|$ is approximately equal to the canonical density matrix $\hat{\rho}_\mathrm{can}=Z^{-1}_\mathrm{can} \exp(-\beta \hat{H}^S)$. Here, we discuss the analogous statement and related questions for the \emph{grand-canonical} density matrix $\hat{\rho}_\mathrm{gc}=Z^{-1}_\mathrm{gc} \exp(-\beta(\hat{H}^S-\mu_1 \hat{N}_{1}^S-\ldots-\mu_r\hat{N}_{r}^S))$ with $\hat{N}_{i}^S$ the number operator for molecules of type $i$ in the system $S$. This includes (i) the case of chemical reactions and (ii) that of systems $S$ defined by a spatial region which particles may enter or leave. It includes the statements (a) that the density matrix of the appropriate (generalized micro-canonical) Hilbert subspace $H_\mathrm{gmc} \subset H^S \otimes H^B$ (defined by a micro-canonical interval of total energy and suitable particle number sectors), after tracing out $B$, yields $\hat{\rho}_\mathrm{gc}$; (b) that typical $\Psi$ from $H_\mathrm{gmc}$ have reduced density matrix $\hat{\rho}^S_\Psi$ close to $\hat{\rho}_\mathrm{gc}$; and (c) that the conditional wave function $\psi^S$ of $S$ has probability distribution $\mathrm{GAP}_{\hat{\rho}_\mathrm{gc}}$ if a typical orthonormal basis of $H^B$ is used. That is, we discuss the foundation and justification of both the density matrix and the distribution of the wave function in the grand-canonical case. We also extend these considerations to the so-called generalized Gibbs ensembles, which apply to systems for which some macroscopic observables are conserved.
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https://arxiv.org/abs/2601.03253
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29892a31fd7dcada7e7c8da71e2863e8dc14f702f394eef6a22a31754a92ad7a
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2026-01-07T00:00:00-05:00
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Asymptotic freedom, lost: Complex conformal field theory in the two-dimensional $O(N>2)$ nonlinear sigma model and its realization in the spin-1 Heisenberg chain
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arXiv:2601.02459v1 Announce Type: cross Abstract: The two-dimensional $O(N)$ nonlinear sigma model (NLSM) is asymptotically free for $N>2$: it exhibits neither a nontrivial fixed point nor spontaneous symmetry-breaking. Here we show that a nontrivial fixed point generically does exist in the $\textit{complex}$ coupling plane and is described by a complex conformal field theory (CCFT). This CCFT fixed point is generic in the sense that it has a single relevant singlet operator, and is thus expected to arise in any non-Hermitian model with $O(N)$ symmetry upon tuning a single complex parameter. We confirm this prediction numerically by locating the CCFT at $N = 3$ in a non-Hermitian spin-1 antiferromagnetic Heisenberg chain, finding good agreement between the complex central charge and scaling dimensions and those obtained by analytic continuation of real fixed points from $N\leq 2$. We further construct a realistic Lindbladian for a spin-1 chain whose no-click dynamics are governed by the non-Hermitian Hamiltonian realizing the CCFT. Since the CCFT vacuum is the eigenstate with the smallest decay rate, the system naturally relaxes under dissipative dynamics toward a CFT state, thus providing a route to preparing long-range entangled states through engineered dissipation.
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https://arxiv.org/abs/2601.02459
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2b7c332bb4e1e05933269e84ed47bb3a14f9a17de85a848798033a2733111a8f
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2026-01-07T00:00:00-05:00
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Renormalization Group is the principle behind the Holographic Entropy Cone
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arXiv:2601.02472v1 Announce Type: cross Abstract: We show that every holographic entropy inequality can be recast in the form: `some entanglement wedges reach deeper in the bulk than some other entanglement wedges.' When the inequality is saturated, the two sets of wedges reach equally deep. Because bulk depth geometrizes CFT scales, the inequalities enforce and protect the holographic Renormalization Group.
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https://arxiv.org/abs/2601.02472
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52a71b7636ee0e62a7c3ff8801039672a8b1e12f755e5842338d6b182a31aa5c
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2026-01-07T00:00:00-05:00
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Probing Dark Matter-Electron Interactions with Superconducting Qubits
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arXiv:2601.02474v1 Announce Type: cross Abstract: Quantum device measurements are powerful tools to probe dark matter interactions. Among these, transmon qubits stand out for their ability to suppress external noise while remaining highly sensitive to tiny energy deposits. Ambient galactic halo dark matter interacting with electrons can deposit energy in the qubit, leading to changes in its decoherence time. Recent measurements of transmons have consistently measured, in various experimental setups, a residual contribution to the decoherence time unexplained by thermal noise or known external sources. We use such measurements to set the most stringent laboratory-based constraints to date on dark matter-electron scattering at the keV scale and competitive constraints on dark photon absorption.
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https://arxiv.org/abs/2601.02474
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73c1c5a3772206bfa12db1c561f9cdd08e902d5a2344c752982e90a637c2a8c5
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2026-01-07T00:00:00-05:00
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Superextensive charging speeds in a correlated quantum charger
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arXiv:2601.02477v1 Announce Type: cross Abstract: We define a quantum charger as an interacting quantum system that transfers energy between two drives. The key figure of merit characterizing a charger is its charging power. Remarkably, the presence of long-range interactions within the charger can induce a collective steady-state charging mode that depends superlinearly on the size of the charger, exceeding the performance of noninteracting, parallel units. Using the driven Lipkin-Meshkov-Glick model and power-law interacting spin chains, we show that this effect persists up to a critical system size set by the breakdown of the high-frequency regime. We discuss optimal work output as well as experimentally accessible initial states. The superlinear charging effect can be probed in trapped-ion experiments, and positions interacting Floquet systems as promising platforms for enhanced energy conversion.
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https://arxiv.org/abs/2601.02477
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f787e0fd41cde9965d264399cdf6340fd5c60202b75fdf798b9a4165d23b4bbf
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2026-01-07T00:00:00-05:00
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Does relativistic motion really freeze initially maximal entanglement?
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arXiv:2601.02976v1 Announce Type: cross Abstract: We investigate the relativistic dynamics of quantum entanglement in a four-qubit cluster ($CL_4$) state using a fully operational Unruh-DeWitt detector framework. Contrary to the widely held expectation that the Unruh effect inevitably degrades initially maximal entanglement, we demonstrate that the 1-3 bipartite entanglement of the $CL_4$ state remains strictly maximal for all accelerations, including the infinite-acceleration limit. This result uncovers a previously unexplored phenomenon, namely the ``complete freezing of initially maximal entanglement" under relativistic motion. To the best of our knowledge, this is the first identification and systematic characterization of such a phenomenon within a relativistic framework. These findings overturn the conventional view that acceleration universally diminishes maximal entanglement and establish the $CL_4$ state as a promising resource for quantum information processing in non-inertial or curved-spacetime settings.
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https://arxiv.org/abs/2601.02976
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71e0a7e3be472926f3a872c6d094f972c88b22146647f65325b07d0115d3ea8f
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2026-01-07T00:00:00-05:00
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Multipartite Non-local Magic and SYK Model
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arXiv:2601.03076v1 Announce Type: cross Abstract: We investigate the structure of quantum magic in interacting disordered fermionic systems, quantifying non-stabilizerness via the fermionic stabilizer R\'enyi entropy (SRE). To resolve the distribution of magic across different scales, we introduce a multipartite non-local magic functional, constructed from an inclusion-exclusion combination of subsystem contributions. This measure serves as a fine-grained diagnostic, isolating genuinely global contributions and revealing nontrivial interactions between local and collective supports of magic. We illustrate the measure on paradigmatic multipartite states and apply these diagnostics to the Sachdev-Ye-Kitaev model and its variants. Crucially, for thermal/typical ensembles, we observe a marked disparity between Thermal Pure Quantum (TPQ) states and the thermal density matrix. This reveals a concealed complexity: the immense computational hardness characterizing the unitary evolution is encoded in the specific microstructure of the black hole microstates, while being washed out in the coarse-grained thermodynamic description. Furthermore, in $\mathcal N=2$ supersymmetric SYK, we show that while fortuitous BPS states exhibit intermediate stabilizer complexity, the multipartite measure unveils a rich, sector-dependent pattern of global correlations, distinguishing them from generic chaotic states.
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https://arxiv.org/abs/2601.03076
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56725ae2a5c00f6306a1cda40963c12d0cb4684485ae7ff42d20f42e96eb5993
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2026-01-07T00:00:00-05:00
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When does entanglement through gravity imply gravitons?
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arXiv:2601.03214v1 Announce Type: cross Abstract: Detection of entanglement through the Newtonian potential has been claimed to support the existence of gravitons, by extrapolating to a thought experiment which demonstrates that complementarity and causality would be in conflict unless quantum fluctuations exist. We critically assess this consistency argument using scalar field models. We show that whether complementarity or no-signalling is violated when quantum fluctuations are neglected, depends on how this approximation is taken, while in both cases entanglement is generated locally in spacetime. We clarify that the correct reading of the paradox requires making a clear distinction between two notions of causality violation: Newtonian action-at-a-distance and the quantum mechanical no-signalling; the latter is pertinent while the former is not. We conclude that the thought experiment (a) does not add to the epistemological relevance of entanglement through Newtonian potentials (b) lends support for the existence of gravitons, if retardation effects are detected in entanglement through gravity.
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https://arxiv.org/abs/2601.03214
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d25b45356b447da738a3b39e23e1e97aba44d3d854a9472defc4eddba7d35113
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2026-01-07T00:00:00-05:00
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Probing negative differential resistance in silicon with a P-I-N diode-integrated T center ensemble
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arXiv:2501.11888v2 Announce Type: replace Abstract: Solid-state defect quantum systems are exquisite probes of their local charge environment. Nonlinear dynamical electric fields in solids are challenging to characterize directly, conventionally limited to coarse macroscopic methods which fail to capture subtle effects in the material. Here, through transient optical spectroscopy on an embedded T center ensemble, we realize the in-situ observation of a silicon PIN-diode phase transition to a regime of self-sustained carrier oscillatory dynamics characteristic of negative differential resistance. Manifest in both the ensemble electroluminescence and photoluminescence, we find a temperature and field-dependent phase space for persistent undamped amplitude oscillations indicative of a collective ensemble response to the field dynamics. These findings shed new light on the cryogenic behavior of silicon, provide fundamental insight into the physics of the T center for improved quantum device performance, and open a promising new direction for defect-based local quantum sensing in semiconductor devices.
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https://arxiv.org/abs/2501.11888
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fb2b7e991ad4e13ee009c8efdc090227e56eb38d09f2392effbd46ebce805ef6
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2026-01-07T00:00:00-05:00
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Efficient quantum simulation for translationally invariant systems
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arXiv:2503.14592v2 Announce Type: replace Abstract: Discrete translational symmetry plays a fundamental role in condensed matter physics and lattice gauge theories, enabling the analysis of systems that would otherwise be intractable. Despite this, many open problems remain. Quantum simulation promises to offer new insights, but progress is often limited by device connectivity constraints, which lead to prohibitively long computation times. We extend the use of spatial symmetry from the systems to be simulated to the quantum circuits simulating them. One application is that it becomes possible to efficiently and optimally alleviate device connectivity constraints algorithmically. This leads to reductions in quantum computational time by several orders of magnitude even for moderate system sizes, making such simulations feasible, with even greater relative gains for larger systems. This substantially enhances the capabilities of quantum computers in the simulation of condensed matter systems and lattice gauge theories, even before hardware improvements. Our work forms the basis for using spatial symmetry of quantum circuits in other areas of quantum computation, such as in the design and implementation of quantum error correcting codes.
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https://arxiv.org/abs/2503.14592
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21fe3a0ae59a7e781fed9f708947937b12be47f8e04ed30ed50220a351ed052b
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2026-01-07T00:00:00-05:00
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The source of hardware-tailored codes and coding phases
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arXiv:2503.15483v2 Announce Type: replace Abstract: A central challenge in quantum error correction is identifying powerful quantum codes tailored to specific hardware and determining their error thresholds above which quantum information is unprotected. This problem is hard because we cannot determine the noise models for our devices. Inspired by the quantum capacity theorem, we seek an optimal quantum source of information, namely the density matrix that degrades minimally when passed through a noisy channel. We explore this idea with the Open Random Unitary Model (ORUM), a simplified model of a $N$-qubit quantum computer with competing depolarizing and dephasing channels as a stand-in for unitary gates and measurements. Through numerical optimization, we find that the ORUM hosts three discrete regimes, three "phases", the "maximally mixed source" phase, a "$\mathbb{Z}_2$ source" phase (where ORUM's $U(1)$ gauge symmetry is broken down to $\mathbb{Z}_2$), and a no-coding phase where all information is lost. These phases exhibit first-order transitions among themselves and converge at a novel zero-capacity multicritical point. These results show a remarkable similarity between the quantum capacity theorem and Jaynes' maximum entropy principle of statistical mechanics. Using the $\mathbb{Z}_2$ source, we build two codes, a classical cat code capable of correcting all the dephasing errors and a concatenated cat code capable of correcting all errors up to a distance $d=\text{min}(m,N)$ and reduces to Shor's 9-qubit code for $m=N=3$. Neither classical nor quantum code survives near the vicinity of the zero-capacity multicritical point in the source phase diagram. Applying our approach to current noisy devices could provide a systematic method for constructing quantum codes for robust computation and communication.
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https://arxiv.org/abs/2503.15483
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870113c88720689125564b7664e6f75769909d4bf9ddd78f9de841f7ec27154a
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2026-01-07T00:00:00-05:00
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Deterministic quantum trajectory via imaginary time evolution
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arXiv:2504.00210v2 Announce Type: replace Abstract: Stochastic quantum trajectories, such as pure state evolutions under unitary dynamics and random measurements, offer a crucial ensemble description of many-body open system dynamics. Recent studies have highlighted that individual quantum trajectories also encode essential physical information. Prominent examples include measurement induced phase transitions, where a pure quantum state corresponding to fixed measurement outcomes (trajectories) exhibits distinct entanglement phases, depending on the measurement rate. However, direct observation of this effect is hindered by an exponential post-selection barrier, whereby the probability of realizing a specific trajectory is exponentially small. We propose a deterministic method to efficiently prepare quantum trajectories in polynomial time using imaginary time evolution and, thus, overcome this fundamental challenge. We demonstrate that our method applies to a certain class of quantum states, and argue that there does not exist universal approaches for any quantum trajectories. Our result paves the way for experimentally exploring the physics of individual quantum trajectories at scale and enables direct observation of certain post-selection-dependent phenomena.
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https://arxiv.org/abs/2504.00210
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490f6757643d8c40a533071962d521b88fc09f1f16f7457a14a966472a3d8071
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2026-01-07T00:00:00-05:00
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Loschmidt echo zeros in finite-size quantum systems with linear quench
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arXiv:2504.00483v2 Announce Type: replace Abstract: Dynamical quantum phase transitions reveal singularities in quench dynamics, characterized by the emergence of Loschmidt echo zeros at critical times, which usually exist only in the thermodynamic limit but are absent in finite-size quantum systems. In this Letter, we propose a theoretical scheme to probe Loschmidt echo zeros in finite-size systems by applying a two-step quenching protocol, which offers an experimentally feasible approach to study Loschmidt echo zeros. Using the transverse Ising model as a test bed, we identify that the exact Loschmidt echo zeros can be always accessed by tuning the quench rate, when the quench is across the phase transition point. The associated rate function displays divergence at critical times, accompanying with the change of the dynamical topological order parameter. The critical times are influenced by the quench rate, system size, and momentum modes, embodying the interplay between finite-size effects and critical dynamics. Moreover, the generality of these observations is further confirmed in the XY and Haldane models.
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https://arxiv.org/abs/2504.00483
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1ee9a8152e49a2085fde89c8a017c80771a5bf6f9548ea990fe10c585e4d84b0
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2026-01-07T00:00:00-05:00
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Markov Gap and Bound Entanglement in Haar Random State
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arXiv:2504.04802v2 Announce Type: replace Abstract: Bound entanglement refers to entangled states that cannot be distilled into maximally entangled states and therefore cannot directly be used in many quantum information processing protocols. We identify a relationship between bound entanglement and the Markov gap, which is introduced within holography via the entanglement wedge cross section and is related to the fidelity of the partial Markov recovery problem. We prove that a bound entangled state must have a nonzero Markov gap. Conversely, for sufficiently large systems, a state with a weakly nonzero Markov gap typically has a bound entangled or separable marginal state, where entanglement is undistillable. Furthermore, this implies that the transition from a bound entangled to a separable state originates from the properties of states with a weakly nonzero Markov gap, which may be dual to non-perturbative effects from a holographic perspective. Our results shed light on the investigation of the Markov gap and enhance interdisciplinary applications of quantum information.
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https://arxiv.org/abs/2504.04802
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0c4de82b33018410fc43e6181cce441cd56815e74c43639befd632af746e7f36
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2026-01-07T00:00:00-05:00
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Matrix-product-state approach for qubits-waveguide systems in real space
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arXiv:2505.19424v2 Announce Type: replace Abstract: We present a matrix-product-state-based numerical approach for simulating systems composed of several qubits and a common one-dimensional waveguide. In the presented approach, the one-dimensional waveguide is modeled in real space. Thus, one can use the advantage of matrix-product states that are suited for simulating low-entangled one-dimensional systems. The price to pay is that the vacuum of the waveguide in this modeling becomes the Bogoliubov vacuum, and one has to consider a not-so-small local Hilbert space for bosonic degrees of freedom. To manage the large local Hilbert space, we adopt the recently proposed single-site schemes. We demonstrate the potential of the presented approach by simulating superradiant phenomena within the Hamiltonian dynamics.
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https://arxiv.org/abs/2505.19424
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e7386e989c6476d731a088dc2689ef53fdb32456c9a2d9126d3e99e6bef08a81
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2026-01-07T00:00:00-05:00
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A Cost-Effective Layout-Aware Quantum Circuit Synthesis For Triangular, Square, and Heavy-Hex Layouts
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arXiv:2506.20098v2 Announce Type: replace Abstract: The quantum layout and the mapping of logical to physical qubits are crucial in quantum circuit synthesis for a real quantum computer. Circuits that include large $n$-bit Toffoli gates ($n \geq 3$), such as those designed from cost-expensive gates and hard-to-decompose Exclusive-or Sum of Products (ESOP) expressions, have complications of effective mappings into contemporary quantum layouts, such as the square grid and heavy-hex layouts. These complications are primarily caused by the limited connectivity among the physical qubits in such layouts, leading to the insertion of many additional SWAP gates. This paper introduces a new quantum circuit synthesis methodology by exploring the advantage of a Positive Davio lattice (PDL) as an intermediate representation to create our proposed triangular layout and layout-aware circuits. From these circuits, we introduce and form the SWAT gate, composed of a SWAP gate followed by a 3-bit Toffoli gate. To illustrate the usefulness of our method for existing industrial quantum layouts, we also introduce cost-effective mappings of the resulting circuits onto square grid and heavy-hex layouts without additional SWAP gates. This is done with the help of the SWAT gate. Our research highlights PDLs as an efficient tool for layout-aware quantum circuit synthesis.
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https://arxiv.org/abs/2506.20098
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a232b116122c65b4f4cb765b17eed1360ac1840970c2bd2853ce540d1acd1430
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2026-01-07T00:00:00-05:00
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Thermodynamic criteria for signaling in quantum channels
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arXiv:2506.20428v2 Announce Type: replace Abstract: Signaling quantum channels are fundamental to quantum communication, enabling the transfer of information from input to output states. In contrast, thermalisation erases information about the initial state. This raises a crucial question: How does the thermalising tendency of a quantum channel constrain its signaling power and vice versa? In this work, we address this question by considering three thermodynamic tasks associated with a quantum channel: the generation, preservation, and transmission of athermality. We provide faithful measures for athermality generation and athermality preservation of quantum channels, and prove that their difference quantifies athermality transmission. Analysing these thermodynamic tasks, we find that the signaling ability of a quantum channel is upper-bounded by its athermality preservation and lower-bounded by its athermality transmission, thereby establishing a fundamental relationship between signaling and thermodynamic properties of channels for quantum communication. We demonstrate this interplay for the example of the quantum switch, revealing an explicit trade-off between the signaling ability and athermality of the quantum channels it can implement.
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https://arxiv.org/abs/2506.20428
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37281e6e6331514035e3e7ea4840391d63964034e5124cfe9a8d73cc6a5712d2
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2026-01-07T00:00:00-05:00
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The Dual Role of Low-Weight Pauli Propagation: A Flawed Simulator but a Powerful Initializer for Variational Quantum Algorithms
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arXiv:2508.06358v2 Announce Type: replace Abstract: Variational quantum algorithms are often hindered by rugged optimization landscapes. In this Letter, we investigate the low-weight Pauli propagation (LWPP) algorithm and find that it serves as an unreliable energy estimator for variational circuits. However, we reveal a counterintuitive insight: the Pauli-weight truncation acts as a spectral filter, effectively smoothing out high-frequency local minima while preserving the global basin of attraction in the landscape. We identify this mechanism as landscape alignment, where the approximate landscape becomes a superior navigator compared to the rugged exact landscape. Benchmarks across diverse spin models and molecular systems demonstrate that LWPP-initialized optimization yields order-of-magnitude improvements in accuracy, often finding solutions inaccessible to direct exact optimization. This work reframes LWPP from a flawed simulator into a vital pre-optimizer that serves not only as a cheap classical substitute but also as an essential tool for addressing quantum optimization challenges.
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https://arxiv.org/abs/2508.06358
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4f7eed1d8cd87a3e77a611b5863684985e57df1e05bf1680cec549f45d10ac24
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2026-01-07T00:00:00-05:00
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Noise-Resilient Spatial Search with Lackadaisical Quantum Walks
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arXiv:2508.13462v2 Announce Type: replace Abstract: Quantum walks are a powerful framework for the development of quantum algorithms, with lackadaisical quantum walks (LQWs) standing out as an efficient model for spatial search. In this work, we investigate how broken-link decoherence affects the performance of LQW-based search on a two-dimensional toroidal grid. We show through numerical simulations that, while decoherence drives the loopless walk toward a uniform distribution and eliminates its search capability, the inclusion of self-loops significantly mitigates this effect. In particular, even under noise, the marked vertex remains identifiable with probability well above uniform, demonstrating that self-loops enhance the robustness of LQWs in realistic scenarios. These findings extend the known advantages of LQWs from the noiseless setting to noisy environments, consolidating self-loops as a valuable resource for designing resilient quantum search algorithms.
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https://arxiv.org/abs/2508.13462
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9c9476cdad2608a4067f7c687aff6328569c8dd29b641076c2ffeda2a1f20928
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2026-01-07T00:00:00-05:00
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Chiral Discrimination on Gate-Based Quantum Computers
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arXiv:2508.18546v2 Announce Type: replace Abstract: We present a novel approach to chiral discrimination using gate-based quantum processors, addressing a key challenge in adapting conventional control techniques using modern quantum computing. Schemes such as stimulated rapid adiabatic passage (STIRAP) and shortcuts to adiabaticity (STAP) have shown strong potential for enantiomer discrimination; their reliance on analog and continuous-time control makes them incompatible with digital gate-based quantum computing architectures. Here, we adapt these protocols for quantum computers by discretizing their Gaussian-shaped pulses through Trotterization. We simulate the chiral molecule 1,2-propanediol and experimentally validate this gate-based implementation on IBM quantum hardware. Our results demonstrate that this approach is a viable foundation for advancing chiral discrimination protocols, preparing the way for quantum-level manipulation of molecular chirality on accessible quantum architectures.
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https://arxiv.org/abs/2508.18546
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cfe89149764ec21aaf8823c7dcd381b595fb2237ac673166c9043e061132ef41
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2026-01-07T00:00:00-05:00
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Hybrid Lattice Surgery: Non-Clifford Gates via Non-Abelian Surface Codes
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arXiv:2510.20890v2 Announce Type: replace Abstract: In universal fault-tolerant quantum computing, implementing logical non-Clifford gates often demands substantial spacetime resources for many error-correcting codes, including the high-threshold surface code. A critical mission for realizing large-scale quantum computing is to develop simple and resource-efficient implementations of logical non-Clifford gates. We propose a novel way of implementing non-Clifford operations in the standard surface code based on hybrid lattice surgery. First we generalize the standard lattice surgery to hybrid lattice surgery, where operations of rough merge and rough split happen across different topological codes. Then we apply such procedures between Abelian and non-Abelian codes and show that this can provide non-Clifford operations in the standard surface code, in the form of a magic state or a non-Clifford gate teleportation. Complementing this, we provide a continuum topological field theory description of this hybrid lattice surgery utilizing interfaces between (2+1)d topological orders. From these considerations, we can generalize our protocol to non-Clifford gates and magic states at all finite levels of the Clifford hierarchy, as well as gates beyond the hierarchy. We also discuss protocols extending this framework to qutrits.
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https://arxiv.org/abs/2510.20890
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Academic Papers
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svg
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a03b6763f453deeacac88c57312de9b7e678bdd05bcfdc3ef84eb70fabe5c956
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2026-01-07T00:00:00-05:00
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Non-commutativity as a Universal Characterization for Enhanced Quantum Metrology
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arXiv:2511.22280v2 Announce Type: replace Abstract: A central challenge in quantum metrology is to effectively harness quantum resources to surpass classical precision bounds. Although recent studies suggest that the indefinite causal order may enable sensitivities to attain the super-Heisenberg scaling, the physical origins of such enhancements remain elusive. Here, we introduce the nilpotency index $\mathcal{K}$, which quantifies the depth of non-commutativity between operators during the encoding process, can act as a fundamental parameter governing quantum-enhanced sensing. We show that a finite $\mathcal{K}$ yields an enhanced scaling of root-mean-square error as $N^{-(1+\mathcal{K})}$. Meanwhile, the requirement for indefinite causal order arises only when the nested commutators become constant. Remarkably, in the limit $\mathcal{K} \to \infty$, exponential precision scaling $N^{-1}e^{-N}$ is achievable. We propose experimentally feasible protocols implementing these mechanisms, providing a systematic pathway towards practical quantum-enhanced metrology.
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https://arxiv.org/abs/2511.22280
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Academic Papers
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svg
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a4e111c47032a49fc930d83edee6c663a1bb60109748a5fd9fa1f05bed794d6d
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2026-01-07T00:00:00-05:00
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Electrical Control of Optically Active Single Spin Qubits in ZnSe
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arXiv:2512.21462v2 Announce Type: replace Abstract: Electrons bound to shallow donors in ZnSe quantum wells are promising candidates for optically addressable spin qubits and single-photon sources. However, their optical coherence and indistinguishability are often limited by spectral broadening arising from charge fluctuations in the local environment. Here, we report electrical control of single donor qubits in ZnSe quantum wells. The applied field induces a DC Stark shift that tunes the emission energy over a range exceeding 30 times the inhomogeneous linewidth, effectively compensating for emitter-to-emitter variations. Concurrently, the field stabilizes trap occupancy, yielding a twofold reduction in optical linewidth and the suppression of spectral wandering. A statistical model based on trap dynamics qualitatively reproduces these observations and elucidates the mechanism of field-assisted charge noise suppression. Our results identify electrical control as a versatile pathway to significantly improve optical and spin addressability.
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https://arxiv.org/abs/2512.21462
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Academic Papers
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svg
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ccb200f3e496e89fa4f2b4a3c7fe7d2b405e5aa1d318ec6ebc3cb66a720d8bf6
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2026-01-07T00:00:00-05:00
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A method for robust spin relaxometry in the presence of imperfect state preparation
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arXiv:2512.22739v2 Announce Type: replace Abstract: Spin relaxometry based on quantum spin systems has developed as a valuable tool in medical and condensed matter systems, offering the advantage of operating without the need for external DC or RF fields. Spin relaxometry with nitrogen-vacancy (NV) centers has been applied to paramagnetic sensing using both single crystal diamond and nanodiamond materials. However, these methods often suffer from artifacts and systematic uncertainties, particularly due to imperfect spin state preparation, leading to artificially fast T$_1$ relaxation times. Current analysis techniques fail to adequately account for these issues, limiting the precision of parameter estimation. In this work, we introduce a minimal fitting procedure that enables more robust parameter estimation in the presence of imperfect spin polarization. Our model improves upon existing approaches by offering more accurate fits and provides a framework for efficiently parallelizing single-spin dynamics studies.
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https://arxiv.org/abs/2512.22739
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Academic Papers
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svg
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9135d7f4b243faf7a3a96d4bc0f71d7d8ed18c50d941dbfba6afdc3a974f845f
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2026-01-07T00:00:00-05:00
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The Equivalence between Hardy-type paradox and Logical Contextuality
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arXiv:2601.01445v2 Announce Type: replace Abstract: Hardy-type paradoxes offer elegant, inequality-free proof of quantum contextuality. In this work, we introduce a unified logical formulation for general Hardy-type paradoxes, which we term logical Hardy-type paradoxes. We prove that for any finite scenario, the existence of a logical Hardy-type paradox is equivalent to logical contextuality. Specially, strong contextuality is equivalent to logical Hardy-type paradoxes with success probability SP = 1. These results generalize prior work on (2,k,2), (2,2,d), and n-cycle scenarios, and resolve a misconception that such equivalence does not hold for general scenarios [1]. We analyse the logical Hardy-type paradoxes on the (2,2,2) and (2,3,3) Bell scenarios, as well as the Klyachko-Can-Binicioglu-Shumovsky (KCBS) scenario. We show that the KCBS scenario admits only one kind of Hardy-type paradox, achieving a success probability of SP \approx 10.56% for a specific parameter setting.
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https://arxiv.org/abs/2601.01445
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Academic Papers
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svg
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956e37c7ed9dd790093ca083d6395f301690ecbe75a89a2855898ece7fbdc7f0
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2026-01-07T00:00:00-05:00
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Preempting Fermion Sign Problem: Unveiling Quantum Criticality through Nonequilibrium Dynamics in Imaginary Time
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arXiv:2410.18854v2 Announce Type: replace-cross Abstract: The notorious fermion sign problem, arising from fermion statistics, presents a fundamental obstacle to the numerical simulation of quantum many-body systems. Here, we introduce a framework that circumvents the sign problem in the studies of quantum criticality and its associated phases by leveraging imaginary-time nonequilibrium critical dynamics. We demonstrate that the critical properties can be accurately determined from the system's short-time relaxation, a regime where the sign problem remains manageable for quantum Monte-Carlo (QMC) simulations. After validating this approach on two benchmark fermionic models, we apply it to the sign-problematic Hubbard model hosting SU(3)-symmetric Dirac fermions. We present the first numerically exact characterization of its quantum phase diagram, revealing a continuous transition between a Dirac semi-metal and a SU(3) antiferromagnetic phase. This transition defines an unconventional Gross-Neveu universality class that fundamentally reshapes current understanding of Gross-Neveu criticality. Our work provides a powerful tool for investigating sign-problematic systems and quantum criticality.
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https://arxiv.org/abs/2410.18854
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Academic Papers
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svg
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7cc1569aae22760fa587fd47c6d683ec0bd8612ad671e6306eb8a92a943a71bd
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2026-01-07T00:00:00-05:00
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The $\theta$-vacuum from functional renormalisation
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arXiv:2507.22318v2 Announce Type: replace-cross Abstract: We study topological properties of a quantum mechanical system with $U(1)$-symmetry within the functional renormalisation group (fRG) approach. These properties include the vacuum energy structure and the topological susceptibility. Our approach works with a complexification of the flow equation, and specifically we embed the original symmetry into the complex plane, $U(1)\rightarrow \mathbb{C}$. We compute the effective potential of a given topological sector by restricting ourselves to field configurations with a given generalised non-trivial Chern-Simons numbers. The full potential is directly constructed from these sector potentials. Our results compare well with the benchmark results obtained from solving the corresponding Schr\"odinger equation.
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https://arxiv.org/abs/2507.22318
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Academic Papers
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svg
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30d497fcbc61540e618240df9f77443871b45a111837d88c2a2af63db1d71ee9
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2026-01-07T00:00:00-05:00
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Variational and field-theoretical approach to exciton-exciton interactions and biexcitons in semiconductors
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arXiv:2510.05242v2 Announce Type: replace-cross Abstract: Bound electron-hole pairs in semiconductors known as excitons are the subject of intense research due to their potential for optoelectronic devices and applications, especially in the realm of two-dimensional materials. While the properties of free excitons in these systems are well understood, a general description of the interactions between these quasiparticles is complicated due to their composite nature, which leads to important exchange processes that can take place between the identical fermions of different excitons. In this work, we employ a variational approach to study interactions between Wannier excitons and obtain an effective interaction potential between two ground-state excitons in a system of spin-degenerate electrons and holes. This potential is in general nonlocal in position space and depends on the combined spin configurations of the electrons and holes. When particularized to the case of hydrogen-like excitons with a heavy hole, this potential becomes local and exactly reproduces the Heitler-London result for two interacting hydrogen atoms. Thus, our result can be interpreted as a generalization of the Heitler-London potential to the case of arbitrary masses. We also show how including corrections due to excited states into the theory results in a van der Waals potential at large distances, which is expected due to the induced dipole-dipole nature of the interactions. Our approach is also applicable to more complicated systems with nonhydrogenic exciton series, such as layered semiconductors with Rytova-Keldysh interactions. Additionally, we use a path-integral formalism to develop a many-body theory for a dilute gas of excitons, resulting in an excitonic action that formally includes many-body interactions between excitons. While in this approach the field representing the excitons is exactly bosonic, we clarify how the internal exchange processes arise in...
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https://arxiv.org/abs/2510.05242
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Academic Papers
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svg
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1afa8bbf5391ae619a194c4ea2e35d9f406cd2250862999ce56385cb888da064
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2026-01-07T00:00:00-05:00
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Site-Order Optimization in the Density Matrix Renormalization Group via Multi-Site Rearrangement
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arXiv:2512.22021v2 Announce Type: replace-cross Abstract: In the approaches based on matrix-product states (MPSs), such as the density-matrix renormalization group (DMRG) method, the ordering of the sites crucially affects the computational accuracy. We investigate the performance of an algorithm that searches for the optimal site order by iterative local site rearrangement. We improve the algorithm by expanding the range of site rearrangement and apply it to a one-dimensional quantum Heisenberg model with random site permutation. The results indicate that increasing the range of the site rearrangement significantly improves the computational accuracy of the DMRG method. In particular, increasing the rearrangement range from two to three sites reduces the average relative error in the ground-state energy by 65% to 94% in the cases we tested. We also discuss the computational cost of the algorithm and its application as a preprocessing for MPS-based calculations.
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https://arxiv.org/abs/2512.22021
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Academic Papers
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svg
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81d517d006350acc8eb9f9a33ef64e42e3575394160fc2cab576fe5b5a52a260
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2026-01-07T00:00:00-05:00
|
Exact Mobility Edges in a Disorder-Free Dimerized Stark Lattice with Effective Unbounded Hopping
|
arXiv:2601.02259v2 Announce Type: replace-cross Abstract: We propose a disorder-free one-dimensional single-particle Hamiltonian hosting an exact mobility edge (ME), placing the system outside the assumptions of no-go theorems regarding unbounded potentials. By applying a linear Stark potential selectively to one sublattice of a dimerized chain, we generate an effective Hamiltonian with unbounded, staggered hopping amplitudes. The unbounded nature of the hopping places the model outside the scope of the Simon-Spencer theorem, while the staggered scaling allows it to evade broader constraints on Jacobi matrices. We analytically derive the bulk spectrum in reciprocal space, identifying a sharp ME where the energy magnitude equals the inter-cell hopping strength. This edge separates a continuum of extended states from two distinct localized branches: a standard unbounded Wannier-Stark ladder and an anomalous bounded branch accumulating at the ME. The existence of extended states is supported by finite-size scaling of the inverse participation ratio up to system sizes $L \sim 10^9$. Furthermore, we propose an experimental realization using photonic frequency synthetic dimensions. Our numerical results indicate that the ME is robust against potential experimental imperfections, including frequency detuning errors and photon loss, establishing a practical path for observing MEs in disorder-free systems.
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https://arxiv.org/abs/2601.02259
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Academic Papers
|
svg
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5c6792474799912692d8b292053d731fc5523e93fe5ff9227f5ee3883c5ff5a2
|
2026-01-07T08:20:27+00:00
|
Trump says Venezuela will turn over oil to US
|
President says money earned from sale of up to 50mn barrels of sanctioned crude ‘will be controlled by me’
|
https://www.ft.com/content/08ca8f8e-6e52-4344-9c0d-2433e98e204c
|
Business & Finance
| |
6cb199eafb163385f4d4f706f75dded4abc95bda45c6087d6202be6f1fa69c0e
|
2026-01-07T05:00:28+00:00
|
Hedge funds hunt for Venezuela’s unpaid financial claims
|
US capture of Nicolás Maduro lifts hopes that country will make good on some debt
|
https://www.ft.com/content/2c04228d-2f2b-49d7-bbed-974053e285b9
|
Business & Finance
| |
c2a1806f70d2b4cda688355cbc9d2d43862ad2137e36bb92e1a0a8de7ad726d7
|
2026-01-06T22:56:13+00:00
|
Polymarket refuses to pay bets that US would ‘invade’ Venezuela
|
Prediction market disputes US raid amounted to an invasion in fight over more than $10.5mn in wagers
|
https://www.ft.com/content/985ae542-1ab4-491e-8e6e-b30f6a3ab666
|
Business & Finance
| |
a64203584b85aa821dd990bc1064b8165548b25a5e9e15ec99abf7ff274ab06d
|
2026-01-07T05:00:28+00:00
|
Cuba: what is left for Trump to topple?
|
Washington hopes Nicolás Maduro’s capture will hasten the downfall of the ossified communist regime in Havana
|
https://www.ft.com/content/d859d893-1e2a-4ae6-a3d4-c9c505954f16
|
Business & Finance
| |
00674f375cd24e4aa93c65912bd685d567e17703517dffb71ab082329ef860ae
|
2026-01-07T05:00:19+00:00
|
Don’t be fooled — everything has changed for the global economy
|
Damage caused by US tariffs has so far been muted but that won’t last
|
https://www.ft.com/content/9c8212b8-568f-4ea2-829a-9b7a13b93f1d
|
Business & Finance
| |
1392d13d49d5266b374790bd829195857ab8e03de7ea59f521c10bb8b150be0a
|
2026-01-07T05:00:19+00:00
|
Watch out for America’s activist attorneys-general
|
Top state lawyers are joining together to challenge Trump and rein in big business
|
https://www.ft.com/content/74dcb89a-9aed-4fba-b07a-f360c8824394
|
Business & Finance
| |
95fff20cf5fff38ad638164813e926384280610666caa8d91e3e7f6a87f55e28
|
2026-01-07T08:34:03+00:00
|
US says using military is among ‘options’ to acquire Greenland
|
White House says annexation of semi-autonomous territory from Denmark is ‘national security priority’
|
https://www.ft.com/content/28485ea3-68ce-4897-8b74-b728d54b5479
|
Business & Finance
| |
9885cfa56e73ee4c6a081d7928ae54d1155c55087ce27b11a38aed2cb8834812
|
2026-01-07T05:00:28+00:00
|
Chevron and Quantum Capital Group line up bid for $22bn of Lukoil assets
|
Trump administration signals support for proposal to divvy up sanctioned Russian company’s international businesses
|
https://www.ft.com/content/20e6d968-54c9-40ce-b9fd-bc066a908fff
|
Business & Finance
| |
33f4541dd5be0452b50bd4e0a5db4f757763ff98fc1cf5955cfb123bee154936
|
2026-01-07T05:00:07+00:00
|
Italy’s Meloni plans voting system overhaul to aid re-election bid
|
Governments have repeatedly tweaked electoral rules in their favour over past decades
|
https://www.ft.com/content/af940a0e-9a46-4d19-a2f8-174fddfcbe19
|
Business & Finance
| |
f29d094cbd3195d728b8cd160f88ec389027b5d3016a11d14282db2896b7502b
|
2026-01-07T05:00:07+00:00
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European banks poised for €30bn interest income rebound
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Loan growth and hedging help bolster banking sector profitability
|
https://www.ft.com/content/017dba93-bf22-424d-9b9a-8e01ec30d769
|
Business & Finance
| |
b5eca780fadfcf1254a8e3f882d34554f485cc679f1fc8150a7a11d28c95b294
|
2026-01-07T07:37:00+00:00
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Trump says Venezuela will send U.S. up to 50 million barrels of oil — and he’ll control the proceeds
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President Donald Trump late Tuesday said Venezuela will send the U.S. 30 million to 50 million barrels of oil, which will then be sold by the U.S. and the proceeds controlled by him.
|
https://www.marketwatch.com/story/trump-says-venezuela-will-send-u-s-up-to-50-million-barrels-of-oil-and-hell-control-the-proceeds-5e05efa0?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-65571761
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67b00c29a2e4035a60d905c7ba09a266e2b6603e404db3e81233daa0e3586aac
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2026-01-06T23:34:00+00:00
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As Tesla’s stock falls, Elon Musk brushes off Nvidia’s competitive threat
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Nvidia is ramping up its work on driverless vehicle technology, a field dominated by Tesla and a few other players. But Musk doesn’t see an imminent reason to worry.
|
https://www.marketwatch.com/story/elon-musk-is-brushing-off-nvidias-attempt-to-take-on-tesla-554a8134?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-75710561
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f5663d789dd22c897d9a11117d9dc8cb7863c44605bec070ab4c6d1145494df9
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2026-01-06T23:29:00+00:00
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Why Sandisk’s stock just soared to its best day in 11 months
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Memory and storage stocks reigned supreme in 2025 and are leading the pack once again to start 2026.
|
https://www.marketwatch.com/story/why-sandisks-stock-is-soaring-toward-its-best-day-in-11-months-9f4a51c6?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-57413903
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204559e41354b49acb39d32340c2df9bb33de839ce72c29c28a47e0771df93e4
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2026-01-06T23:21:00+00:00
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Strategy’s stock is rising as investors get some much-needed good news
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Strategy gets to stay in MSCI indexes for now — though the index provider says it will launch a more general review of whether investment-oriented companies can keep their spots.
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https://www.marketwatch.com/story/strategys-stock-is-rising-as-investors-get-some-much-needed-good-news-971e0f9f?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-41914565
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a16d1b8d89ee1e953a56438a41ac68d82677d53d22fe7d48b25346e0724d59cb
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2026-01-06T23:13:00+00:00
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I’m retired and selling my home after 35 years — what’s changed since the ‘90s?
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Retirees need to learn a lot before undertaking the task. They are wise to begin long before listing their homes.
|
https://www.marketwatch.com/story/planning-to-sell-your-home-in-retirement-do-these-tasks-first-ef5cb0b4?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-91316090
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94770df7e673eb8ff9c92a4f1edc7f0342563c78523cabc17e73582ea7f333d0
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2026-01-06T23:10:00+00:00
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Why U.S. oil refiners could be the big winners in Venezuela — even if its actual reserves disappoint
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Refiners in the U.S. have the distinctive ability to handle the type of heavy crude Venezuela claims to have in abundance.
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https://www.marketwatch.com/story/why-u-s-oil-refiners-could-be-the-big-winners-in-venezuela-even-if-its-actual-reserves-disappoint-6a9a6b1a?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-44400636
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7d992204d287dd1775012c06b3dd5b4cca4e88f4e7c7660358f7e228feaed6ef
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2026-01-06T22:59:00+00:00
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‘He even bragged about his Mercedes-Benz:’ I rejected two egotistical advisers. I managed my life savings and they tripled over 25 years. Did I do OK?
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“We do not take out-of-country or five-star vacations. Instead, we enjoy time with family and friends and hobbies.”
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https://www.marketwatch.com/story/he-even-bragged-about-his-mercedes-benz-i-rejected-two-egotistical-advisers-i-managed-my-life-savings-and-they-tripled-over-25-years-did-i-do-ok-148d5d2e?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-62429339
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2624c82fbc4949572ceecafd35c660d2c080a78d8aa1e000b7220e430121d649
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2026-01-06T22:41:00+00:00
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‘We track our finances religiously’: Are we obliged to pay for our daughter’s medical school? We have $2.6 million saved for retirement.
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“I am retired, and my wife is an employed physician. She is 56 and would like to retire as well.”
|
https://www.marketwatch.com/story/we-track-our-finances-religiously-do-we-pay-for-our-daughters-medical-school-weve-2-6-million-for-retirement-acd99b84?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-42962860
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ed3563e1a416b9e74068796ee4adfbdbb074725f80e41cb3794d06997a4ba54a
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2026-01-06T22:28:00+00:00
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Elon Musk is taking on ChatGPT — and xAI now has $20 billion more to do it
|
Cisco Investments and Nvidia were strategic investors in a newly announced funding round.
|
https://www.marketwatch.com/story/elon-musk-is-taking-on-chatgpt-and-xai-now-has-20-billion-more-to-do-it-ec28bc2d?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-84875009
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a6686f47d177b52f289a2bc1c992ae3809f871d91e8222f77491afad3bf550c7
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2026-01-06T22:04:00+00:00
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What you need to know about changes to Social Security, Medicare and Medicaid in 2026
|
Here’s a rundown of what retirees and savers can expect in the coming year.
|
https://www.marketwatch.com/story/what-you-need-to-know-about-changes-to-social-security-medicare-and-medicaid-in-2026-549b2f8c?mod=mw_rss_topstories
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Business & Finance
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https://images.mktw.net/im-22332988
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c73b995790b584ca061a070fb186a2144cee608f4a6f88ed47addf97e7839269
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2026-01-07T07:54:23+00:00
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Why Trump wants Greenland — and what makes it so important for national security
|
Greenland, a vast and sparsely populated self-governing Danish territory, has been thrust into the geopolitical spotlight once again.
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https://www.cnbc.com/2026/01/07/why-trump-wants-greenland-and-what-makes-it-so-important-for-security.html
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Business & Finance
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svg
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