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f66588b241423fd76212e1460fabedca05270406da4c040719e05424068712fa
2026-01-23T00:00:00-05:00
A Fast Monte Carlo Newton-Raphson Algorithm to Estimate Generalized Linear Mixed Models with Dense Covariance
arXiv:2601.16022v1 Announce Type: new Abstract: Estimation of Generalised linear mixed models (GLMM) including spatial Gaussian process models is often considered computationally impractical for even moderately sized datasets. In this article, we propose a fast Monte Carlo maximum likelihood (MCML) algorithm for the estimation of GLMMs. The algorithm is a stochastic Newton-Raphson method, which approximates the expected Hessian and gradient of the log-likelihood by drawing samples of the random effects. We propose a new stopping criterion for efficient termination and preventing long runs of sampling in the stationary post-convergence phase of the algorithm and discuss Monte Carlo sample size choice. We run a series of simulation comparisons of spatial statistical models alongside the popular integrated nested Laplacian approximation method and demonstrate potential for similar or improved estimator performance and reduced running times. We also consider scaling of the algorithms to large datasets and demonstrate a greater than 100-fold reduction in running times using modern GPU hardware to illustrate the feasibility of full maximum likelihood methods with big spatial datasets.
https://arxiv.org/abs/2601.16022
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6f1f882b45339b2256608c340f4245513a5072c6303a428f1e233ce5e3c82146
2026-01-23T00:00:00-05:00
A forward-only scheme for online learning of proposal distributions in particle filters
arXiv:2601.16089v1 Announce Type: new Abstract: We introduce a new online approach for constructing proposal distributions in particle filters using a forward scheme. Our method progressively incorporates future observations to refine proposals. This is in contrast to backward-scheme algorithms that require access to the entire dataset, such as the iterated auxiliary particle filters (Guarniero et al., 2017, arXiv:1511.06286) and controlled sequential Monte Carlo (Heng et al., 2020, arXiv:1708.08396) which leverage all future observations through backward recursion. In comparison, our forward scheme achieves a gradual improvement of proposals that converges toward the proposal targeted by these backward methods. We show that backward approaches can be numerically unstable even in simple settings. Our forward method, however, offers significantly greater robustness with only a minor trade-off in performance, measured by the variance of the marginal likelihood estimator. Numerical experiments on both simulated and real data illustrate the enhanced stability of our forward approach.
https://arxiv.org/abs/2601.16089
Academic Papers
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a549a27dc5b37812de42cc71edff4adb4fae5c32f443d00918f361924787dafa
2026-01-23T00:00:00-05:00
Inference on the Significance of Modalities in Multimodal Generalized Linear Models
arXiv:2601.16196v1 Announce Type: new Abstract: Despite the popular of multimodal statistical models, there lacks rigorous statistical inference tools for inferring the significance of a single modality within a multimodal model, especially in high-dimensional models. For high-dimensional multimodal generalized linear models, we propose a novel entropy-based metric, called the expected relative entropy, to quantify the information gain of one modality in addition to all other modalities in the model. We propose a deviance-based statistic to estimate the expected relative entropy, prove that it is consistent and its asymptotic distribution can be approximated by a non-central chi-squared distribution. That enables the calculation of confidence intervals and p-values to assess the significance of the expected relative entropy for a given modality. We numerically evaluate the empirical performance of our proposed inference tool by simulations and apply it to a multimodal neuroimaging dataset to demonstrate its good performance on various high-dimensional multimodal generalized linear models.
https://arxiv.org/abs/2601.16196
Academic Papers
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bf54aa2d698534ffa18d8765fbb8b86598985a1ed298e0d158571293547f31fb
2026-01-23T00:00:00-05:00
Sequential model confidence sets
arXiv:2404.18678v4 Announce Type: replace Abstract: In most prediction and estimation situations, scientists consider various statistical models for the same problem, and naturally want to select amongst the best. Hansen et al. (2011) provide a powerful solution to this problem by the so-called model confidence set, a subset of the original set of available models that contains the best models with a given level of confidence. Importantly, model confidence sets respect the underlying selection uncertainty by being flexible in size. However, they presuppose a fixed sample size which stands in contrast to the fact that model selection and forecast evaluation are inherently sequential tasks where we successively collect new data and where the decision to continue or conclude a study may depend on the previous outcomes. In this article, we extend model confidence sets sequentially over time by relying on sequential testing methods. Recently, e-processes and confidence sequences have been introduced as new, safe methods for assessing statistical evidence. Sequential model confidence sets allow to continuously monitor the models' performances and come with time-uniform, nonasymptotic coverage guarantees.
https://arxiv.org/abs/2404.18678
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aa0412ac013a01a3819f6164adc43825e0f6d819a29ad2f77664701ae7782c2d
2026-01-23T00:00:00-05:00
Spectral decomposition-assisted multi-study factor analysis
arXiv:2502.14600v2 Announce Type: replace Abstract: This article focuses on covariance estimation for multi-study data. Popular approaches employ factor-analytic terms with shared and study-specific loadings that decompose the variance into (i) a shared low-rank component, (ii) study-specific low-rank components, and (iii) a diagonal term capturing idiosyncratic variability. Our proposed methodology estimates the latent factors via spectral decompositions, with a novel approach for separating shared and specific factors, and infers the factor loadings and residual variances via surrogate Bayesian regressions. The resulting posterior has a simple product form across outcomes, bypassing the need for Markov chain Monte Carlo sampling and facilitating parallelization. The proposed methodology has major advantages over current Bayesian competitors in terms of computational speed, scalability and stability while also having strong frequentist guarantees. The theory and methods also add to the rich literature on frequentist methods for factor models with shared and group-specific components of variation. The approximation error decreases as the sample size and the data dimension diverge, formalizing a blessing of dimensionality. We show favorable asymptotic properties, including central limit theorems for point estimators and posterior contraction, and excellent empirical performance in simulations. The methods are applied to integrate three studies on gene associations among immune cells.
https://arxiv.org/abs/2502.14600
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01d69cc512caa1a4f65d2d7d8def358602b0723caee06d19ab005a71254ca162
2026-01-23T00:00:00-05:00
Not All Accuracy Is Equal: Prioritizing Independence in Infectious Disease Forecasting
arXiv:2509.21191v2 Announce Type: replace Abstract: Ensemble forecasts have become a cornerstone of large-scale disease response, underpinning decision making at agencies such as the US Centers for Disease Control and Prevention (CDC). Their growing use reflects the goal of combining multiple models to improve accuracy and stability versus relying on any single model. However, while ensembles regularly demonstrate stability against individual model failures, improved accuracy is not guaranteed. During the COVID-19 pandemic, the CDC's multi-model ensemble outperformed the best single model by only 1\%, and CDC flu ensembles have often ranked below individual models. Prior work has established that ensemble performance depends critically on diversity: when models make independent errors, combining them yields substantial gains. In practice, however, this diversity is often lacking. Here, we propose that this is due in part to how models are developed and selected: both modelers and ensemble builders optimize for stand-alone accuracy rather than ensemble contribution, and most epidemic forecasts are built from a small set of approaches trained on the same surveillance data. The result is highly correlated errors, limiting the benefit of ensembling. This suggests that in developing models and ensembles, we should prioritize models that contribute complementary information rather than replicating existing approaches. We present a toy example illustrating the theoretical cost of correlated errors, analyze correlations among COVID-19 forecasting models, and propose improvements to model fitting and ensemble construction that foster genuine diversity. Ensembles built with this principle in mind produce forecasts that are more robust and more valuable for epidemic preparedness and response.
https://arxiv.org/abs/2509.21191
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2ddf0cf41fb4359b3f3f4aa12320adb83c5910be7a7c822a1bbc04295612b661
2026-01-23T00:00:00-05:00
regTPS-KLE: A Novel Approach To Approximate A Gaussian Random Field for Bayesian Spatial Modeling
arXiv:2510.04256v2 Announce Type: replace Abstract: Gaussian random field is a ubiquitous model for spatial phenomena in diverse scientific disciplines. Its approximation is often crucial for computational feasibility in simulation, inference, and uncertainty quantification. The Karhunen-Lo\`eve Expansion provides a theoretically optimal basis for representing a Gaussian random field as a sum of deterministic orthonormal functions weighted by uncorrelated random variables. While this is a well-established method for dimension reduction and approximation of (spatial) stochastic processes, its practical application depends on the explicit or implicit definition of the covariance structure. In this work, we propose a novel approach, referred to as regTPS-KLE, for approximating a Gaussian random field by explicitly constructing its covariance via a regularized thin plate spline (TPS) kernel. Because TPS kernels are conditionally positive definite and lack a direct spectral decomposition, we formulate the covariance as the inverse of a regularized elliptic operator. To evaluate its statistical performance, we compare its predictive accuracy and computational efficiency with a Gaussian random field approximation constructed using the stochastic partial differential equations (SPDE) method and implemented within an MCMC algorithm. In simulation studies, the predictive differences between the SPDE and regTPS-KLE models were minimal when the spatial field was generated using Mat\`ern and exponential covariance functions, while regTPS-KLE models consistently outperformed the SPDE approach in terms of computational efficiency. In a real data application, regTPS-KLE exhibits superior predictive accuracy compared with SPDE models based on leave-one-out cross-validation while also achieving improved computational efficiency.
https://arxiv.org/abs/2510.04256
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87700743729cd44a81fc4da58f9ad305b73e969396e598a69a83bc7b588376e2
2026-01-23T00:00:00-05:00
RESOLVE-IPD: High-Fidelity Individual Patient Data Reconstruction and Uncertainty-Aware Subgroup Meta-Analysis
arXiv:2511.01785v2 Announce Type: replace Abstract: Individual patient data (IPD) from oncology trials are essential for reliable evidence synthesis but are rarely publicly available, necessitating reconstruction from published Kaplan-Meier (KM) curves. Existing reconstruction methods suffer from digitization errors, unrealistic uniform censoring assumptions, and the inability to recover subgroup-level IPD when only aggregate statistics are available. We developed RESOLVE-IPD, a unified computational framework that enables high-fidelity IPD reconstruction and uncertainty-aware subgroup meta-analysis to address these limitations. RESOLVE-IPD comprises two components. The first component, High-Fidelity IPD Reconstruction, integrates the VEC-KM and CEN-KM modules: VEC-KM extracts precise KM coordinates and explicit censoring marks from vectorized figures, minimizing digitization error, while CEN-KM corrects overlapping censor symbols and eliminates the uniform censoring assumption. The second component, Uncertainty-Aware Subgroup Recovery, employs the MAPLE (Marginal Assignment of Plausible Labels and Evidence Propagation) algorithm to infer patient-level subgroup labels consistent with published summary statistics (e.g., hazard ratio, median overall survival) when subgroup KM curves are unavailable. MAPLE generates ensembles of mathematically valid labelings, facilitating a propagating meta-analysis that quantifies and reflects uncertainty from subgroup reconstruction. RESOLVE-IPD was validated through a subgroup meta-analysis of four trials in advanced esophageal squamous cell carcinoma, focusing on the programmed death ligand 1 (PD-L1)-low population. RESOLVE-IPD enables accurate IPD reconstruction and robust, uncertainty-aware subgroup meta-analyses, strengthening the reliability and transparency of secondary evidence synthesis in precision oncology.
https://arxiv.org/abs/2511.01785
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21297120490fc6218e6616c5244a3e6906c3bbe26bb7e1d882959f6348600872
2026-01-23T00:00:00-05:00
Recent advances in the Bradley--Terry Model: theory, algorithms, and applications
arXiv:2601.14727v2 Announce Type: replace Abstract: This article surveys recent progress in the Bradley-Terry (BT) model and its extensions. We focus on the statistical and computational aspects, with emphasis on the regime in which both the number of objects and the volume of comparisons tend to infinity, a setting relevant to large-scale applications. The main topics include asymptotic theory for statistical estimation and inference, along with the associated algorithms. We also discuss applications of these models, including recent work on preference alignment in machine learning. Finally, we discuss several key challenges and outline directions for future research.
https://arxiv.org/abs/2601.14727
Academic Papers
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e88fc09835d5d5b88d4d93a880e3a7a784ac002361fce430915401832feefca0
2026-01-23T00:00:00-05:00
Precision limit under weak-coupling with ancillary qubit
arXiv:2601.15354v1 Announce Type: new Abstract: We propose a measurement-based quantum metrology protocol in a composite model, where the probe system (a spin ensemble) is coupled to an ancillary two-level system (qubit) with a general Heisenberg XXZ interaction. With an optimized and weak probe-ancilla coupling strength and a proper duration of joint evolution, the two parallel evolution paths of the probe system induced by the unconditional measurement on qubit can transform an eigenstate of the collective angular momentum operator of spin ensemble to be a two-component state with a large distance in eigenspace. The quantum Fisher information about the phase encoded in the probe system of polarized states or their superposition, that could be relaxed to mixed states, can therefore manifest an exact or asymptotic quadratic scaling with respect to the probe size (spin number) $N$. The quadratic scaling behavior is found to be insensitive to the imperfect encoding operator and coupling strength. By virtue of the parity detection on the ancillary qubit or the probe system, the phase sensitivity can approach the Heisenberg limit. We suggest that the unconditional measurement on qubit could become an efficient resource to replace Greenberger-Horne-Zeilinger-like states and squeezing Hamiltonian for exceeding the standard quantum limit in metrology precision.
https://arxiv.org/abs/2601.15354
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91905284e3b224f3f27edaa55542a65af66882700005b63a7d948146ee8e0b3d
2026-01-23T00:00:00-05:00
Dissipative Quantum Dynamics in Static Network with Different Topologies
arXiv:2601.15439v1 Announce Type: new Abstract: We investigate the dissipative dynamics of quantum population and coherence among different network topologies of a quantum network using a quantum spin model coupled to a thermal bosonic reservoir. Our study proceeds in two parts. First, we analyze a small network of Ising spins embedded in a large dissipative bath, modeled via the Lindblad master equation, where temperature arises naturally from system-bath coupling. This approach reveals how network topology shapes quantum dissipative dynamics, providing a basis for controlling quantum coherence through tailored network structures. Second, we propose a mean-field approach that extends the network to larger scales and captures dissipative dynamics in large-scale networks, connecting network topology to quantum coherence in complex systems and revealing the sensitivity of quantum coherence to network structure. Our results highlight how dissipative quantum dynamics depend on network topology, providing insight into the coherent dynamics of entangled states in networks. These results may be extended to dynamics in complex systems such as opinion propagation in social models, epidemiology, and various condensed-phase and biological systems.
https://arxiv.org/abs/2601.15439
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a82a70db43dab9447f1eb6f761527c2760bda91addfeaca5eb48c1837124b900
2026-01-23T00:00:00-05:00
Check-weight-constrained quantum codes: Bounds and examples
arXiv:2601.15446v1 Announce Type: new Abstract: Quantum low-density parity-check (qLDPC) codes can be implemented by measuring only low-weight checks, making them compatible with noisy quantum hardware and central to the quest to build noise-resilient quantum computers. A fundamental open question is how constraints on check weight limit the achievable parameters of qLDPC codes. Here, we study stabilizer and subsystem codes with constrained check weight, combining analytical arguments with numerical optimization to establish strong upper bounds on their parameters. We show that stabilizer codes with checks of weight at most three cannot have nontrivial distance. We also prove tight tradeoffs between rate and distance for broad families of CSS stabilizer and subsystem codes with checks of weight at most four and two, respectively. Notably, our bounds are applicable to general qLDPC codes, as they rely only on check-weight constraints without assuming geometric locality or special graph connectivity. In the finite-size regime, we derive numerical upper bounds using linear programming techniques and identify explicit code constructions that approach these limits, delineating the landscape of practically relevant qLDPC codes with tens or hundreds of physical qubits.
https://arxiv.org/abs/2601.15446
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f3f05c397360c6a8aefa2815e0307e8776a720a0c7f4a91a45de66c25cc85495
2026-01-23T00:00:00-05:00
NWQWorkflow: The Northwest Quantum Workflow
arXiv:2601.15521v1 Announce Type: new Abstract: This whitepaper presents NWQWorkflow, an end-to-end workflow for quantum application development, compilation, error correction, benchmarking, numerical simulation, control, and execution on a prototype superconducting testbed. NWQWorkflow integrates NWQStudio (programming GUI environment), NWQASM (intermediate representation), QASMTrans (compiler), NWQEC (quantum error correction), QASMBench (benchmarking and characterization), NWQSim (HPC simulation), NWQLib (algorithm library), NWQData (data sets), NWQControl (quantum control), and NWQSC (superconducting testbed). The system enables closed-loop software-hardware co-design and reflects the past eight years of quantum computing research the author has led at PNNL (2018-2026). By releasing most software components as open source or planning their open-source availability, we aim to cultivate a collaborative quantum information science (QIS) ecosystem and support the transition toward a scalable quantum supercomputing era.
https://arxiv.org/abs/2601.15521
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b14918047615c26b5386d836e1dbce78da3cfc2fb7ee76071003e4558a25f3de
2026-01-23T00:00:00-05:00
A Sublinear-Time Quantum Algorithm for High-Dimensional Reaction Rates
arXiv:2601.15523v1 Announce Type: new Abstract: The Fokker-Planck equation models rare events across sciences, but its high-dimensional nature challenges classical computers. Quantum algorithms for such non-unitary dynamics often suffer from exponential {decay in} success probability. We introduce a quantum algorithm that overcomes this for computing reaction rates. Using a sum-of-squares representation, we develop a Gaussian linear combination of Hamiltonian simulations (Gaussian-LCHS) to represent the non-unitary propagator with $O\left(\sqrt{t\|H\|\log(1/\epsilon)}\right)$ queries to its block encoding. Crucially, we pair this with {a} novel technique to directly estimate matrix elements without exponential decay. For $\eta$ pairwise interacting particles discretized with $N$ plane waves per degree of freedom, we estimate reactive flux to error $\epsilon$ using $\widetilde{O}\left((\eta^{5/2}\sqrt{t\beta}\alpha_V + \eta^{3/2}\sqrt{t/\beta}N)/\epsilon\right)$ quantum gates, where $\alpha_V = \max_{r}|V'(r)/r|$. For non-convex potentials, the {sharpest classical} worst-case analytical bounds to simulate the related overdamped Langevin {equation} scale as $O(te^{\Omega(\eta)}/\epsilon^4)$. This {implies} an exponential separation in particle number $\eta$, a quartic speedup in $\epsilon$, and quadratic speedup in $t$. While specialized classical heuristics may outperform these bounds in practice, this demonstrates a rigorous route toward quantum advantage for high-dimensional dissipative dynamics.
https://arxiv.org/abs/2601.15523
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da95a0b56c5d83f02e3a11042d079775935328ef7798152e9b62d4962616ac9c
2026-01-23T00:00:00-05:00
Spectator-transition crosstalk in a spin-3/2 silicon vacancy qudit in silicon carbide revealed by broadband Ramsey interferometry
arXiv:2601.15559v1 Announce Type: new Abstract: Color center spins in 4H-SiC offer a rare combination of wafer-scale materials maturity with long spin coherence and chip-level photonics, making them promising building blocks for scalable quantum technologies. In particular, the silicon vacancy hosts an S=3/2 ground state, a native qudit that enables compact encodings and subspace-selective control, but also introduces spectator transitions: short, detuned pulses can coherently drive non-addressed level pairs and create crosstalk. Here we use broadband Ramsey interferometry to reveal and quantify such spectator-transition crosstalk. Experimentally, the Ramsey Fourier spectra display multiple lines beyond the addressed single-quantum transition. Analytically, we map each line to a pairwise energy difference between qudit levels of the rotating-frame Hamiltonian and assign its weight via compact amplitudes set by the prepared state and the microwave pulse parameters, predicting a deterministic six-branch structure. Numerical time-domain propagation with the experimental sampling reproduces the detuning map, and the measured peak positions coincide with the analytic branch lines without frequency fitting. Together these results provide a practical, spectator-aware framework for multilevel control in the silicon vacancy qudit. The approach offers clear guidance to suppress crosstalk or, conversely, to exploit spectator lines, for example as additional constraints for in situ pulse calibration and for phase-sensitive quantum state and process estimation.
https://arxiv.org/abs/2601.15559
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009a85840fc20441d6ef6f2d5763b9dd71e5736b4ba37eefd5635e5b5a3d40f6
2026-01-23T00:00:00-05:00
Optimized Slice-Phase Control of Mirror Pulse in Cold-Atom Interferometry with Finite Response Time
arXiv:2601.15586v1 Announce Type: new Abstract: Atom interferometers require both high efficiency and robust performance in their mirror pulses under experimental inhomogeneities. In this work, we demonstrated that quantum optimal control designed mirror pulse significantly enhance interferometer performance by using novel adaptive sliced structure. Using gradient ascent pulse engineering (GRAPE), optimized mirror pulse for a Mach-Zehnder light-pulse atom interferometer was designed by discretizing the control into non-uniform phase slices. This design broadened the tolerence to experimentally relevant variations in detuning $[-\Omega_0,\Omega_0]$ and Rabi frequency $[0.1\times\Omega_0,1.9\times\Omega_0]$ ($\Omega_0=2\pi\times25$ kHz), while maintaining high transfer efficiency even when the response-time delays up to 1.6 $\rm{\mu s}$. The optimized pulse was found to be robust to coupling inhomogeneity and velocity spread, offering a significant improvement in robustness over conventional pulse. The adaptive pulse slicing method provides a minimalist strategy that reduces experimental complexity while enhancing robustness and scalability, offering an innovative scheme for quantum optimal control in high precision atom interferometry.
https://arxiv.org/abs/2601.15586
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b58c7ccbd1578053cb7bf62bdb41321ff6b01e8a9ac89a25bef081b3a09d2c67
2026-01-23T00:00:00-05:00
Tensor-based phase difference estimation on time series analysis
arXiv:2601.15616v1 Announce Type: new Abstract: We propose a phase-difference estimation algorithm based on the tensor-network circuit compression, leveraging time-evolution data to pursue scalability and higher accuracy on a quantum phase estimation (QPE)-type algorithm. Using tensor networks, we construct circuits composed solely of nearest-neighbor gates and extract time-evolution data by four-type circuit measurements. In addition, to enhance the accuracy of time-evolution and state-preparation circuits, we propose techniques based on algorithmic error mitigation and on iterative circuit optimization combined with merging into matrix product states, respectively. Verifications using a noiseless simulator for the 8-qubit one-dimensional Hubbard model using an ancilla qubit show that the proposed algorithm achieves accuracies with 0.4--4.7\% error from a true energy gap on an appropriate time-step size, and that accuracy improvements due to the algorithmic error mitigation are observed. We also confirm the enhancement of the overlap with matrix product states through iterative optimization. Finally, the proposed algorithm is demonstrated on IBM Heron devices with Q-CTRL error suppression for 8-, 36-, and 52-qubit models using more than 5,000 2-qubit gates. These largest-scale demonstrations for the QPE-type algorithm represent significant progress not only toward practical applications of near-term quantum computing but also toward preparation for the era of error-corrected quantum devices.
https://arxiv.org/abs/2601.15616
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f0771c5b2137c883fcde97fc4541ecfbaa11e3b4afeb49b7be7ed7f3fc8d6f05
2026-01-23T00:00:00-05:00
Quantum-HPC hybrid computation of biomolecular excited-state energies
arXiv:2601.15677v1 Announce Type: new Abstract: We develop a workflow within the ONIOM framework and demonstrate it on the hybrid computing system consisting of the supercomputer Fugaku and the Quantinuum Reimei trapped-ion quantum computer. This hybrid platform extends the layered approach for biomolecular chemical reactions to accurately treat the active site, such as a protein, and the large and often weakly correlated molecular environment. Our result marks a significant milestone in enabling scalable and accurate simulation of complex biomolecular reactions
https://arxiv.org/abs/2601.15677
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6f940b765d0790662faa6c7cc994a223a05636fa38d5aa1e689c39c669a49ca8
2026-01-23T00:00:00-05:00
Fractional squeezing: spectra and dynamics from generalized squeezing Hamiltonian with fractional orders
arXiv:2601.15693v1 Announce Type: new Abstract: We generalize the generalized-squeezing problem to include fractional values of the squeezing order $n$. This approach allows us to determine the locations of critical points at which qualitative changes in behaviour occur and accurately predict the behaviour at these critical points, which are challenging for conventional computational methods. Based on our numerical calculations, we identify with a high degree of confidence the point at which the spectrum turns from continuous to discrete and the point at which oscillations turn from having asymptotically infinite amplitudes to finite amplitudes. Furthermore, we numerically investigate the behaviour in the large $n$ regime and provide an intuitive explanation that coincides with the numerical results.
https://arxiv.org/abs/2601.15693
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338674d274c9c7a7dff76b82142b8d90183e928f2c031cf44ae2440e60846d35
2026-01-23T00:00:00-05:00
Unsplit Spreading: An Overlooked Signature of Long-Range Interaction
arXiv:2601.15752v1 Announce Type: new Abstract: In conventional lattice models, the dispersion relation $\omega(k)$ is assumed to be a smooth function. We prove that this smoothness implies the splitting of an initially localized excitation into counter-propagating wave packets. Consequently, unsplit spreading can occur only when $\omega(k)$ develops singular features, precisely what long-range interactions enable. Remarkably, this phenomenon was clearly visible in published quantum simulation experiments as early as 2014, yet it has remained unrecognized or discussed as a distinct physical effect. We show that unsplit spreading emerges in realistic open quantum systems, such as 1D and 2D subwavelength atomic arrays, where the long-lived subradiant states host effective dispersion with the required singularities. Our work establishes unsplit spreading as an experimentally accessible, smoking-gun signature of singular band structure induced by long-range physics.
https://arxiv.org/abs/2601.15752
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aa9207422f5b31fd4158aa2ec4c8438fa7be428ebd9cac6e68194c30100956d8
2026-01-23T00:00:00-05:00
Improving the efficiency of QAOA using efficient parameter transfer initialization and targeted-single-layer regularized optimization with minimal performance degradation
arXiv:2601.15760v1 Announce Type: new Abstract: Quantum approximate optimization algorithm (QAOA) have promising applications in combinatorial optimization problems (COPs). We investigated the MaxCut problem in three different families of graphs using QAOA ansats with parameter transfer initialization followed by targeted single layer optimization. For 3 regular (3R), Erdos Renyi (ER), and Barabasi Albert (BA) graphs, the parameter transfer approach achieved mean approximation ratios of 0.9443 for targeted-single layer optimization as compared to 0.9551 of full optimization. It represents 98.88 percent optimal performance, with 8.06 times computational speedup in unweighted graphs. But, in weighted graph families, optimal performance is relatively low (less than 90 percent) for higher nodes graph, suggesting parameter transfer followed by targeted-single-layer optimization is not ideal for weighted graph families, however, we find that for some weighted families (weighted 3-regular) this approach works perfectly. In 8.92 percent test cases, targeted single layer optimization outperformed the full optimization, indicating that complex parameter landscape can trap full optimization in sub-optimal local minima. To mitigate this inconsistency, ridge (L2) regularization is used to smoothen the solution landscape, which helps the optimizer to find better optimum parameters during full optimization and reduces these inconsistent test cases from 8.92 percent to 3.81 percent. This work demonstrates that efficient parameter initialization and targeted-single-layer optimization can improve the efficiency of QAOA with minimal performance degradation.
https://arxiv.org/abs/2601.15760
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a2f8fc4bd7c24b4f26dfdf773e3dedfe33198084ba2bb6450c080be03eba3d98
2026-01-23T00:00:00-05:00
Classical Simulation of Noiseless Quantum Dynamics without Randomness
arXiv:2601.15770v1 Announce Type: new Abstract: Simulating noiseless quantum dynamics classically faces a fundamental dilemma: tensor-network methods become inefficient as entanglement saturates, while Pauli-truncation approaches typically rely on noise or randomness. To close the gap, we propose the Low-weight Pauli Dynamics (LPD) algorithm that efficiently approximates local observables for short-time dynamics in the absence of noise. We prove that the truncation error admits an average-case bound without assuming randomness, provided that the state is sufficiently entangled. Counterintuitively, entanglement--usually an obstacle for classical simulation--alleviates classical simulation error. We further show that such entangled states can be generated either by tensor-network classical simulation or near-term quantum devices. Our results establish a rigorous synergy between existing classical simulation methods and provide a complementary route to quantum simulation that reduces circuit depth for long-time dynamics, thereby extending the accessible regime of quantum dynamics.
https://arxiv.org/abs/2601.15770
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5d571f2d4ddc2f4abd4ce8ef53faa2a2a54358cd7208776f6a40d270105f7d25
2026-01-23T00:00:00-05:00
Fermion Doubling in Dirac Quantum Walks
arXiv:2601.15885v1 Announce Type: new Abstract: We consider discrete spacetime models known as quantum walks, which can be used to simulate Dirac particles. In particular we look at fermion doubling in these models, in which high momentum states yield additional low energy solutions which behave like Dirac particles. The presence of doublers carries over to the `second quantised' version of the walks represented by quantum cellular automata, which may lead to spurious solutions when introducing interactions. Moreover, we also consider pseudo-doublers, which have high energy but behave like low energy Dirac particles, and cause potential problems regarding the stability of the vacuum. To address these issues, we propose a family of quantum walks, that are free of these doublers and pseudo-doublers, but still simulate the Dirac equation in the continuum limit. However, there remain a small number of additional low energy solutions which do not directly correspond to Dirac particles. While the conventional Dirac walk always has a zero probability for the walker staying at the same point, we obtain the family of walks by allowing this probability to be non-zero.
https://arxiv.org/abs/2601.15885
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e5997a8be47fa1f18ec366edbed2816ed6d3174582585310629f087010c74df1
2026-01-23T00:00:00-05:00
Improved cryptographic security in teleportation with q-deformed non-maximal entangled states
arXiv:2601.15902v1 Announce Type: new Abstract: In this work the machinery of q-deformed algebras are used to enhance cryptographic security during teleportation. We use q-deformed harmonic oscillator states to develop a novel method of teleportation. The deformed states can be expressed in terms of standard oscillator states and the expressions contain certain arbitrary functions of $q$. It is the presence of these arbitrary functions that allows an enhancement of cryptographic security. The specifics are : (a) q-deformed Bell-like states are constructed which reduce to the usual Bell states when the deformation parameter $q\rightarrow 1$. These deformed states form an orthonormal basis for q-deformed entangled bipartite states when certain arbitrary functions of $q$ satisfy a constraint. (b) We discuss the generalisation of the usual teleportation protocol with non-maximally entangled states. This generalisation is then employed to construct two new protocols using q-deformed non-maximally entangled states. These states have additional parameters and these have to be shared for decryption after teleportation. Consequently, the cryptographic security is improved.
https://arxiv.org/abs/2601.15902
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1ded13620a263687470c0cc096fe982b7af2e03379fb4c4dcc2fb5663ef609e4
2026-01-23T00:00:00-05:00
Automated quantum circuit optimization with randomized replacements
arXiv:2601.15934v1 Announce Type: new Abstract: Quantum circuit optimization - the process of transforming a quantum circuit into an equivalent one with reduced time and space requirements - is crucial for maximizing the utility of current and near-future quantum devices. While most automated optimization techniques focus on transforming circuits into equivalent ones that implement the same unitary, we show that substantial new opportunities for resource reduction can be achieved by (1) allowing approximate local transformations and (2) employing mixed quantum channels to approximate pure circuits. Our novel automated protocol for approximate circuit rewriting is a refined evolution of automated optimization techniques based on the ZX-calculus, where we add a greedy strategy that selectively replaces ZX-diagrams with small phase angles with stochastic mixtures of the identity and carefully chosen over-rotations, which are designed to reduce the overall gate count in expectation while staying within a strict error budget. This approach yields modest two-qubit gate count reduction in random quantum circuits, and achieves a substantial reduction in structured circuits such as the quantum Fourier transform. Fundamentally, our protocol converts experimental noise due to gate applications into deliberately engineered random noise, outperforming many other approximation methods on average. These results highlight the potential of mixed-channel approximations to enhance future quantum circuit performance, suggesting new directions for resource-aware automated quantum compilation beyond pure unitary channels.
https://arxiv.org/abs/2601.15934
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600720fe029e17a026141511d9012095729a03bfef9d680c2b7b6e0c61b5a4d4
2026-01-23T00:00:00-05:00
Frictional work and entropy production in integrable and non-integrable spin chains
arXiv:2601.15941v1 Announce Type: new Abstract: The maximum work extractable from a quantum system is achieved when the system is driven adiabatically. Frictional work then quantifies the difference in work output between adiabatic and non-adiabatic driving. Here we show that frictional work in a non-integrable spin chain is well-described by the diagonal entropy production associated with the build up of quantum coherence. The relationship is characterized by an effective temperature of the final adiabatic state and holds for slow to moderate driving protocols. For fast protocols, the frictional work is instead described by the quantum relative entropy between the final non-adiabatic and adiabatic states. We compare our results to those obtained from an integrable spin chain, in which case the adiabatic state is no longer described by a single temperature. In this case, the frictional work is described by a sum of terms for each independent subspace of the spin chain, which are at different effective temperatures. We show how integrability breaking can enhance work extraction in the adiabatic limit, but degrade work extraction in sufficiently non-adiabatic regimes.
https://arxiv.org/abs/2601.15941
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5c4a17d10337b76d77d6324e215cfeed39c9880a8e8eec11a798ddba5d5dbcdd
2026-01-23T00:00:00-05:00
Renormalization Treatment of IR and UV Cutoffs in Waveguide QED and Implications to Numerical Model Simulation
arXiv:2601.15945v1 Announce Type: new Abstract: We present a non-perturbative, first-principles derivation of renormalization relations for waveguide-QED models, explicitly accounting for the infrared (IR) and ultraviolet (UV) cutoffs that are necessarily introduced in numerical simulations. By formulating the atomic dynamics in the time domain, we obtain explicit expressions linking the bare model parameters to the physically observable atomic frequency and decay rate, and verify their consistency with scattering theory. We further connect these results to standard Feynman diagrams, providing a transparent physical interpretation and ensuring the generality of the approach. Finally, we show how these renormalization relations can be used to parameterize simulations with a minimal frequency bandwidth, simultaneously preserving physical accuracy and reducing computational cost, thereby paving the way for efficient and reliable multi-photon light-matter simulations.
https://arxiv.org/abs/2601.15945
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9bdfc3b0d6f9dedc7ec0b1388fc5890f94d16db70715fb2ec5db2f4ea5db242c
2026-01-23T00:00:00-05:00
Universal Digitized Counterdiabatic Driving
arXiv:2601.15972v1 Announce Type: new Abstract: Counterdiabatic driving realizes parameter displacement of an energy eigenstate of a given parametrized Hamiltonian using the adiabatic gauge potential. In this paper, we propose a universal method of digitized counterdiabatic driving, constructing the adiabatic gauge potential in a digital way with the idea of universal counterdiabatic driving. This method has three advantages over existing universal counterdiabatic driving and/or digitized counterdiabatic driving: it does not introduce any many-body and/or nonlocal interactions to an original target Hamiltonian; it can incorporate infinite nested commutators, which constitute the adiabatic gauge potential; and it gives explicit expression of rotation angles for digital implementation. We show the consistency of our method to the exact theory in an analytical way and the effectiveness of our method with the aid of numerical simulations.
https://arxiv.org/abs/2601.15972
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d483a967869c4d9e42d82d5732c00e21c9b4ee52e44e7bf034309a533633919a
2026-01-23T00:00:00-05:00
Semiclassical entanglement entropy for spin-field interaction
arXiv:2601.15986v1 Announce Type: new Abstract: We study a general bipartite quantum system consisting of a spin interacting with a bosonic field, with the initial state prepared as the product of a spin coherent state and a canonical coherent state. Our goal is to develop a semiclassical framework to describe the entanglement dynamics between these two subsystems. Using appropriate approximations, we derive a semiclassical expression for the entanglement entropy that depends exclusively on the trajectories of the underlying classical description. By analytically extending the classical phase space into the complex domain, we identify additional complex trajectories that significantly improve the accuracy of the semiclassical description. The inclusion of these complex trajectories allows us to capture the entanglement dynamics with remarkable precision, even well beyond the Ehrenfest time. The approach is illustrated with a representative example, where the role of real and complex trajectories in reproducing the quantum entanglement entropy is explicitly demonstrated.
https://arxiv.org/abs/2601.15986
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2a90e8ef971dd20537b2f31ded70c564d950c2abc7588b7c4e110362ec43f270
2026-01-23T00:00:00-05:00
Engineering quantum Mpemba effect by Liouvillian skin effect
arXiv:2601.16002v1 Announce Type: new Abstract: We propose a new approach to engineer the quantum Mpemba effect (QME) -- wherein an initial state farther from system relaxes faster than a close one -- by the Liouvillian skin effect (LSE) in open quantum systems. Moreover, the LSE serves as an ideal platform for realizing the QME and the spatial profile of the LSE provides a straightforward pathway for the initial state preparation, thereby enabling readily accessible experimental preparation. Focusing on the quadratic Lindbladians, we consider two concrete cases to design the initial states, thereby realizing the QME. Interestingly, we uncover a new kind of QME (QME-III) that is distinct from the two typical scenarios, manifested as two reversals in the Hilbert-Schmidt distance at two different times. In particular, the LSE provides a physically more intuitive understanding of the QME.
https://arxiv.org/abs/2601.16002
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cbbdc2cbc58934df17ba50531d7ae5fe0f7947aff8f5ac2d5927922664df713a
2026-01-23T00:00:00-05:00
Echoed Random Quantum Metrology
arXiv:2601.16026v1 Announce Type: new Abstract: Quantum metrology typically demands the preparation of exotic quantum probe states, such as entangled or squeezed states, to surpass classical limits. However, the need for carefully calibrated system parameters and finely optimized quantum controls imposes limitations on scalability and robustness. Here, we circumvent these limitations by introducing an echoed random process that achieves sensitivity approaching the Heisenberg limit while remaining blind to the random probe state. We demonstrate that by simply driving a Kerr nonlinear mode with random pulses, the emergence of sub-Planck phase-space structures grants high sensitivity, eliminating the need for complex quantum control. The protocol is statistically robust, yielding high performance across broad driving parameter ranges while exhibiting resilience to control fluctuations and photon loss. Broadly applicable to both bosonic and qubit platforms, our work reveals a practical, hardware-efficient, scalable, and optimization-free route to quantum-enhanced metrology in high-dimensional Hilbert spaces.
https://arxiv.org/abs/2601.16026
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401f8c14afeed38fcc4855bdb4b2b17fc9568e06868688fd9ad506ab4d3534fa
2026-01-23T00:00:00-05:00
Robust Quantum Algorithmic Binary Decision-Making on Displacement Signals
arXiv:2601.16081v1 Announce Type: new Abstract: A relevant signal in the quantum domain may manifest as a displacement or a phase shift operator in the bosonic phase space. For a real parameter $\beta$ embedded in such a displacement operator, the task of determining if $\beta \in [\beta_{-th}, \beta_{+th}]$ for real asymmetric thresholds $(\beta_{-th} \ne -\beta_{+th})$ is a binary decision problem. We propose a framework based on generalized quantum signal processing interferometry (GQSPI) on hybrid qubit-bosonic oscillator systems that addresses this parameter detection problem by recasting the practical task of active binary hypothesis testing on quantum systems to that of a polynomial approximation. We achieve a small decision error probability $p_{err}$ on the order of $O(\frac{1}{d}\log{(d)})$, with $d$ as the circuit depth. We analyze the protocol when (i) $\beta$ is a deterministic parameter, and (ii) when $\beta$ is drawn randomly from a known prior distribution. The performance of the sensing protocol under dephasing noise is also shown to be robust. We further extend our protocol from two thresholds to more general multi-threshold cases as well. Overall, the proposed framework enables decision-making over arbitrary thresholds for any general displacement signal in a single or a few shots.
https://arxiv.org/abs/2601.16081
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170caa91475c6cf924388d9e6da8b6f871528dcae25f2cc8c7405ca051288143
2026-01-23T00:00:00-05:00
Quantum Metrology under Coarse-Grained Measurement
arXiv:2601.16106v1 Announce Type: new Abstract: While quantum metrology enables measurement precision beyond classical limits, its performance is often susceptible to experimental imperfections. Most prior studies have focused on imperfections in quantum states and operations. Here, we investigate the effect of coarse graining in quantum measurement through both theoretical analysis and experimental demonstration. Using an interferometer with a squeezed vacuum and a laser input, we analyze how coarse graining in homodyne detection affects the precision of phase estimation. We evaluate the Fisher information under various coarse-graining conditions and determine, in each case, an optimal estimation strategy that saturates the Cram\'{e}r-Rao bound. Remarkably, even extremely coarse-grained measurement -- with only two bins -- enables phase estimation beyond the standard quantum limit and even achieves a precision that follows the Heisenberg scaling. We experimentally demonstrate quantum-enhanced phase estimation under coarse-grained homodyne detection. To determine an optimal estimation strategy, we employ the method of moments and present calibration procedures that enable its application to general experimental settings. Using only two bins, we observe a quantum enhancement of 1.2 dB compared to the classical method using the ideal measurement, improving towards 3.8 dB as the bin number increases. These results highlight a practical pathway to achieving quantum enhancement under the presence of severe experimental imperfections.
https://arxiv.org/abs/2601.16106
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176708b5b66e4f88e166a1c4885cd1fdc85b92bd8d67f5527424ac96c264bf95
2026-01-23T00:00:00-05:00
Experimental prime factorization via a feedback quantum control
arXiv:2601.16116v1 Announce Type: new Abstract: Prime factorization on quantum processors is typically implemented either via circuit-based approaches such as Shor's algorithm or through Hamiltonian optimization methods based on adiabatic, annealing, or variational techniques. While Shor's algorithm demands high-fidelity quantum gates, Hamiltonian optimization schemes, with prime factors encoded as degenerate ground states of a problem Hamiltonian, generally require substantial classical post-processing to determine control parameters. We propose an all-quantum, measurement-based feedback approach that iteratively steers a quantum system toward the target ground state, eliminating the need for classical computation of drive parameters once the problem Hamiltonian is determined and realized. As a proof of principle, we experimentally factor the biprime 551 using a three-qubit NMR quantum register and numerically analyze the robustness of the method against control field-errors. We further demonstrate scalability by numerically implementing the FALQON factorization of larger biprimes, 9,167 and 2,106,287, using 5 and 9 qubits, respectively.
https://arxiv.org/abs/2601.16116
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32c6ef89a85d43910ca8f32a9531204a857be50dfcf1f3273f8dbef083f2ddda
2026-01-23T00:00:00-05:00
Calibration-Conditioned FiLM Decoders for Low-Latency Decoding of Quantum Error Correction Evaluated on IBM Repetition-Code Experiments
arXiv:2601.16123v1 Announce Type: new Abstract: Real-time decoding of quantum error correction (QEC) is essential for enabling fault-tolerant quantum computation. A practical decoder must operate with high accuracy at low latency, while remaining robust to spatial and temporal variations in hardware noise. We introduce a hardware-conditioned neural decoder framework designed to exploit the natural separation of timescales in superconducting processors, where calibration drifts occur over hours while error correction requires microsecond-scale responses. By processing calibration data through a graph-based encoder and conditioning a lightweight convolutional backbone via feature-wise linear modulation (FiLM), we decouple the heavy processing of device statistics from the low-latency syndrome decoding. We evaluate this approach using the 1D repetition code as a testbed on IBM Fez, Kingston, and Pittsburgh processors, collecting over 2.7 million experimental shots spanning distances up to d = 11. We demonstrate that a single trained model generalizes to unseen qubit chains and new calibration data acquired days later without retraining. On these unseen experiments, the FiLM-conditioned decoder achieves up to an 11.1x reduction in logical error rate relative to modified minimum-weight perfect matching. We observe that by employing a network architecture that exploits the highly asynchronous nature of system calibration and decoding, hardware-conditioned neural decoding demonstrates promising, adaptive performance with negligible latency overhead relative to unconditioned baselines.
https://arxiv.org/abs/2601.16123
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183c4a8c3d0e13e1f7b1b6ce230f28e0af6555f388d36ffdc8051896f22e9ef6
2026-01-23T00:00:00-05:00
Quantum Dimension Reduction of Hidden Markov Models
arXiv:2601.16126v1 Announce Type: new Abstract: Hidden Markov models (HMMs) are ubiquitous in time-series modelling, with applications ranging from chemical reaction modelling to speech recognition. These HMMs are often large, with high-dimensional memories. A recently-proposed application of quantum technologies is to execute quantum analogues of HMMs. Such quantum HMMs (QHMMs) are strictly more expressive than their classical counterparts, enabling the construction of more parsimonious models of stochastic processes. However, state-of-the-art techniques for QHMM compression, based on tensor networks, are only applicable for a restricted subset of HMMs, where the transitions are deterministic. In this work we introduce a pipeline by which \emph{any} finite, ergodic HMM can be compressed in this manner, providing a route for effective quantum dimension reduction of general HMMs. We demonstrate the method on both a simple toy model, and on a speech-derived HMM trained from data, obtaining favourable memory--accuracy trade-offs compared to classical compression approaches.
https://arxiv.org/abs/2601.16126
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e44501ac88e219eb89f102a371449cc3dfe97069d4ebcaabfaa9361923916ae2
2026-01-23T00:00:00-05:00
Fair sampling with temperature-targeted QAOA based on quantum-classical correspondence theory
arXiv:2601.16144v1 Announce Type: new Abstract: In combinatorial optimization problems with degenerate ground states, fair sampling of degenerate solutions is essential. However, the quantum approximate optimization algorithm (QAOA) with a standard transverse-field mixer induces biases among degenerate states as circuit depth increases. Based on quantum-classical correspondence theory, we propose SBO-QAOA, which employs a temperature-dependent Hamiltonian encoding a Gibbs distribution as its ground state. Numerical simulations show that, unlike standard QAOA, SBO-QAOA yields ground-state probabilities converging to finite-temperature values with uniform distribution among degenerate states. These fairness and temperature-targeting properties are preserved even with only four variational parameters under a linear schedule.
https://arxiv.org/abs/2601.16144
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425c890bec5f6ea5cf4f2e23cfd5eaa7d70832c450090402a095f19ab5d49b1a
2026-01-23T00:00:00-05:00
Polynomial-time thermalization and Gibbs sampling from system-bath couplings
arXiv:2601.16154v1 Announce Type: new Abstract: Many physical phenomena, including thermalization in open quantum systems and quantum Gibbs sampling, are modeled by Lindbladians approximating a system weakly coupled to a bath. Understanding the convergence speed of these Lindbladians to their steady states is crucial for bounding algorithmic runtimes and thermalization timescales. We study two such families of processes: one characterizing a repeated-interaction Gibbs sampling algorithm, and another modeling open many-body quantum thermalization. We prove that both converge in polynomial time for several non-commuting systems, including high-temperature local lattices, weakly interacting fermions, and 1D spin chains. These results demonstrate that simple dissipative quantum algorithms can prepare complex Gibbs states and that Lindblad dynamics accurately capture thermal relaxation. Our proofs rely on a novel technical result that extrapolates spectral gap lower bounds from quasi-local Lindbladians to the non-local generators governing these dynamics.
https://arxiv.org/abs/2601.16154
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53af02ab2de8f9ae19d7f6e553913d1358903ab2df00379938970010b520ff4d
2026-01-23T00:00:00-05:00
Stabilizer Thermal Eigenstates at Infinite Temperature
arXiv:2601.16177v1 Announce Type: new Abstract: Understanding how to analyze highly entangled thermal eigenstates is a central challenge in the study of quantum many-body systems. In this Letter, we introduce a stabilizer-based approach to construct analytically tractable energy eigenstates of nonintegrable many-body Hamiltonians. Focusing on zero-energy eigenstates at infinite temperature, we prove a sharp no-go theorem: stabilizer eigenstates of two-body Hamiltonians cannot satisfy $k$-body microscopic thermal equilibrium for any $k\ge4$. We further show that this bound is tight by explicitly constructing two-body nonintegrable Hamiltonians whose stabilizer eigenstates reproduce thermal expectation values for all two-body and all three-body observables. Finally, we identify the structural origin of this limitation by characterizing the conditions under which a stabilizer state can appear as a zero-energy eigenstate of a Hamiltonian, thereby revealing a fundamental constraint imposed by the few-body nature of interactions.
https://arxiv.org/abs/2601.16177
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28a3e23ecd28cdb701ee8d4c039944c5a3788a646576fda968763e85d7747150
2026-01-23T00:00:00-05:00
Studying energy-resolved transport with wavepacket dynamics on quantum computers
arXiv:2601.16180v1 Announce Type: new Abstract: Probing energy-dependent transport in quantum simulators requires preparing states with tunable energy and small energy variance. Existing approaches often study quench dynamics of simple initial states, such as computational basis states, which are far from energy eigenstates and therefore limit the achievable energy resolution. In this work, we propose using wavepackets to probe transport properties with improved energy resolution. To demonstrate the utility of this approach, we prepare and evolve wavepackets on Quantinuum's H2-2 quantum computer and identify an energy-dependent localization transition in the Anderson model on an 8x7 lattice--a finite-size mobility edge. We observe that a wavepacket initialized at low energy remains spatially localized under time evolution, while a high-energy wavepacket delocalizes, consistent with the presence of a mobility edge. Crucial to our experiments is an error mitigation strategy that infers the noiseless output bit string distribution using maximum-likelihood estimation. Compared to post-selection, this method removes systematic errors and reduces statistical uncertainty by up to a factor of 5. We extend our methods to the many-particle regime by developing a quantum algorithm for preparing quasiparticle wavepackets in a one-dimensional model of interacting fermions. This technique has modest quantum resource requirements, making wavepacket-based studies of transport in many-body systems a promising application for near-term quantum computers.
https://arxiv.org/abs/2601.16180
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f51af83b109a4a0f226be1615f4c921b770ce4b45c7b614ee918ff6e387c2371
2026-01-23T00:00:00-05:00
Robust Bell Nonlocality from Gottesman-Kitaev-Preskill States
arXiv:2601.16189v1 Announce Type: new Abstract: Bell tests based on homodyne detection are strongly constrained in continuous-variable systems. Can Gottesman-Kitaev-Preskill (GKP) encoding turn homodyne detection into a practical tool for revealing Bell nonlocality? We consider a physically motivated model in which each party performs homodyne detection and digitizes the continuous outcome via a fixed periodic binning, corresponding to logical Pauli measurements. Within this framework, we derive a bipartite no-go: CHSH cannot be violated for Bell-pair states. Moving beyond two parties, we show that finitely squeezed GKP-encoded GHZ and W states nevertheless exhibit strong multipartite nonlocality, violating multipartite Bell inequalities with homodyne-only readout. We quantify the required squeezing thresholds and robustness to loss, providing a route toward homodyne-based Bell tests in continuous-variable systems.
https://arxiv.org/abs/2601.16189
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551e38017a9fabf40e2309cac6d3c094c6941aacbd9c57d4ff3f8a1cac1e357e
2026-01-23T00:00:00-05:00
Quantum scientists for disarmament: a manifesto
arXiv:2601.14282v1 Announce Type: cross Abstract: We, as researchers in quantum science and technology, are publishing this manifesto to express our deep concerns about the current geopolitical situation and the global race to rearm. We firmly oppose all forms of militarization in our societies and, in particular, within the academic world. We categorically reject the use of our research for military applications, population control, or surveillance. We stand against the practice of military funding for research. This manifesto is a call to action: to confront the elephant in the room of quantum research, and to unite all researchers who share our views. Our main goals are: i) To express, as a unified collective, our rejection of the use of our research for military purposes; ii) To open a debate in our community about the ethical implications of quantum research for military purposes; iii) To create a forum where concerned scientists can share their opinions and join forces in support of demilitarized research; iv) To advocate for the establishment of a public database listing all research projects at public universities funded by military or defense agencies. In what follows, we lay out our concerns and the rationale behind our opposition to the militarization of quantum research.
https://arxiv.org/abs/2601.14282
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77bd808ffe66e61ba76478366d2841c3cad0d37bae54571e3afb943ee7c6ef51
2026-01-23T00:00:00-05:00
Non-zero Momentum Implies Long-Range Entanglement When Translation Symmetry is Broken in 1D
arXiv:2601.15345v1 Announce Type: cross Abstract: A result by Gioia and Wang [Phys Rev X 12, 031007 (2022)] showed that translationally symmetric states having nonzero momentum are necessarily long range entangled (LRE). Here, we consider the question: can a notion of momentum for non-translation symmetric states directly encode the nature of their entanglement, as it does for translation symmetric states? We show the answer is affirmative for 1D systems, while higher dimensional extensions and topologically ordered systems require further work. While Gioia and Wang's result applies to states connected via finite depth quantum circuits to a translation symmetric state, it is often impractical to find such a circuit to determine the nature of the entanglement of states that break translation symmetry. Here, instead of translation eigenstates, we focus on the many-body momentum distribution and the expectation value of the translation operator in many-body states of systems having broken translation symmetry. We show that in the continuum limit the magnitude of the expectation value of the translation operator $||$ necessarily goes to $1$ for delocalized states, a proxy for LRE states in 1D systems. This result can be seen as a momentum-space version of Resta's formula for the localization length. We investigate how accurate our results are in different lattice models with and without well-defined continuum limits. To that end, we introduce two models: a deterministic version of the random dimer model, illustrating the role of the thermodynamic and continuum limits for our result at a lattice level, and a simplified version of the Aubry-Andre model, with commensurate hopping for both momentum and position space. Finally, we use the random dimer model as a test case for the accuracy of $||$ as a localization (and thus entanglement) probe for 1D periodic lattice models without a well-defined continuum limit.
https://arxiv.org/abs/2601.15345
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a93746847473bf12b83e8712c508a0b14ac9a90ec37c4fcdf145087337691a41
2026-01-23T00:00:00-05:00
In-Substrate Imaging of Diamond hBN FET Current via Widefield Quantum Diamond Microscopy
arXiv:2601.15355v1 Announce Type: cross Abstract: We demonstrate widefield magnetic imaging of current flow in hydrogen terminated diamond field effect transistors (FETs) through in-substrate nitrogen vacancy (NV) centers. Hydrogen termination of the diamond surface induces a two dimensional hole gas (2DHG), while an ensemble of near surface NV centers located $ \sim 1~\mu m$ below the surface enables noninvasive magnetic imaging of current flow with micrometer scale spatial resolution. The FETs were electrically characterized over a range of drain source biases $V_{ds}= 0$ to $-15V$ and gate voltages,$V_{gs}= +3$ to $-9V$ followed by in situ widefield NV magnetometry during device operation. Magnetic field maps and reconstructed current density distributions directly visualize current injection at the source drain contacts and transport beneath the hBN gated channel. Magnetic field maps reveal current density variations in the channel region owing to non-uniformities or defects in the gate dielectric. In addition, we observe a pronounced enhancement of the drain current ($\sim 600-900 \mu A$) and a shift in the apparent threshold voltage during laser illumination, reflecting photo induced changes in channel electrostatics. By correlating gate dependent magnetic images with simultaneous electrical measurements, we directly link spatial current distributions to FET transfer characteristics, providing new insight into buried interface transport and non-uniform gating effects in the transistor channel. As the methodology is compatible with top gated FETs, it can be used to map channel current distributions with micrometer resolution in emerging channel materials, such as 2D materials and wide bandgap channels, and establish widefield NV magnetometry as a powerful platform for probing charge transport in transistors and Van der Waals dielectric heterostructures.
https://arxiv.org/abs/2601.15355
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ae33120c56ec3c3e4dd1f95f87f96e3721eb1c2ad728d3460e90f2353f9e4756
2026-01-23T00:00:00-05:00
Exploring Quantumness at Long-Baseline Neutrino Experiments
arXiv:2601.15375v1 Announce Type: cross Abstract: Violations of classicality can be probed through measurements performed on a system at different times, as proposed by Leggett and Garg. Specifically, violations of Leggett-Garg inequalities suggest the presence of quantum effects in macroscopic systems. Long-baseline neutrino experiments provide some of the longest available propagation distances over which such tests can be performed. Previous studies of Leggett-Garg tests in the neutrino sector have largely focused on showing that the oscillation probabilities can violate classical bounds for certain parameter choices. In this work, we develop a more complete and data-driven framework that treats both the distributions representing the classical and quantum behavior, as well as the experimental uncertainties. We consider MINOS, T2K, NOvA, as well as the upcoming DUNE, and present the respective statistical significance for distinguishing quantum behavior from classical scenarios at these long-baseline neutrino experiments. Among them, we find that T2K yields the most significant violation of classicality, at the level of $\sim 14 \sigma$, with NOvA and projections for DUNE also resulting in a significance of more than $5\sigma$.
https://arxiv.org/abs/2601.15375
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535131a15c95318be6336d0c73dbf7aa365c57abf6357682c521538e8402c17c
2026-01-23T00:00:00-05:00
Magic of discrete lattice gauge theories
arXiv:2601.15842v1 Announce Type: cross Abstract: Simulation of quantum field theories and fundamental interactions are one of the most challenging tasks in modern particle physics. Classical computers generally fail to reproduce accurate results when it comes to strongly coupled theories such as QCD. Recent developments in quantum technologies open up the possibility of simulating such physical regimes by using quantum computers. In this paper, we study the quantum resource related to the simulability of a quantum theory, i.e. non-stabilizerness for Lattice Gauge Theory (LGT) with discrete symmetry gauge groups. We show that enforcing gauge constraints for $\mathbb{Z}_l$ LGTs has no cost in terms of this resource and discuss the relation between non-abelianity of the gauge group with the average non-stabilizerness of the gauge invariant Hilbert space.
https://arxiv.org/abs/2601.15842
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aaaa5fd9484cf1ceeef08352e4742d3b6aa744036c81d3967afad451a14582b1
2026-01-23T00:00:00-05:00
Quantum Hall Effect at 0.002T
arXiv:2601.16015v1 Announce Type: cross Abstract: Graphene enables precise carrier-density control via gating, making it an ideal platform for studying electronic interactions. However, sample inhomogeneities often limit access to the low-density regimes where these interactions dominate. Enhancing carrier mobility is therefore crucial for exploring fundamental properties and developing device applications. Here, we demonstrate a significant reduction in external inhomogeneity using a double-layer graphene architecture separated by an ultra-thin hexagonal boron nitride layer. Mutual screening between the layers reduces scattering from random Coulomb potentials, resulting in a quantum mobility exceeding. Shubnikov de-Haas oscillations emerge at magnetic fields below 1 mT, while integer quantum Hall features are observed at 0.002T. Furthermore, we identify a fractional quantum Hall plateau at a filling factor of at 2T. These results demonstrate the platform's suitability for investigating strongly correlated electronic phases in graphene-based heterostructures.
https://arxiv.org/abs/2601.16015
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b5a34ff067e022fecc3fe5d57c4a241254fb3152aaa72cef7353d6bdb8b29960
2026-01-23T00:00:00-05:00
Helical Current of Propagating Dirac Electrons and Geometric Coupling to Chiral Environments
arXiv:2601.16066v1 Announce Type: cross Abstract: We show that a propagating Dirac electron with intrinsic spin generically carries a real--space helical conserved current, even in the absence of orbital angular momentum. Using exact Dirac eigenstates in cylindrical confinement, we demonstrate that this helical structure possesses definite handedness, persists into evanescent regions, and is characterized by a geometric helix pitch independent of the longitudinal de~Broglie wavelength. This intrinsic helical geometry enables a local geometric coupling between a propagating electron and a chiral environment, yielding chirality--dependent spin selectivity through current geometry rather than through a spin--orbit coupling term.
https://arxiv.org/abs/2601.16066
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569ab794e5b5b81648996367ecf1d43662cdddedc842b4c74dae043cec7d26fe
2026-01-23T00:00:00-05:00
String Breaking and Glueball Dynamics in $2+1$D Quantum Link Electrodynamics
arXiv:2601.16166v1 Announce Type: cross Abstract: At the heart of quark confinement and hadronization, the physics of flux strings has recently become a focal point in the field of quantum simulation of high-energy physics (HEP). Despite considerable progress, a detailed understanding of the behavior of flux strings in quantum simulation-relevant lattice formulations of gauge theories has remained limited to the lowest truncations of the gauge field, which are severely limited in their ability to draw conclusions about the quantum field theory limit. Here, we employ tensor network simulations to investigate the behavior of flux strings in a quantum link formulation of $2+1$D quantum electrodynamics (QED) with a spin-$1$ representation of the gauge field. We first map out the ground-state phase diagram of this model in the presence of two spatially separated static charges, revealing distinct microscopic processes responsible for string breaking, including a two-stage breaking mechanism not possible in the spin-$\frac{1}{2}$ formulation. Starting in different initial product state string configurations, we then explore far-from-equilibrium quench dynamics across various parameter regimes, demonstrating genuine $2+1$D real-time string breaking and glueball-like bound state formation, with the latter not possible in the spin-$\frac{1}{2}$ formulation. In and out of equilibrium, we consider different values and placements of the static charges. Finally, we provide efficient qudit circuits for a quantum simulation experiment in which our results can be observed in state-of-the-art ion-trap setups. Our findings lay the groundwork for quantum simulations of flux strings towards the quantum field theory limit.
https://arxiv.org/abs/2601.16166
Academic Papers
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4188deb576215aa053b844a3faab2a65a5047a0933568bc9e577004e4abb8aea
2026-01-23T00:00:00-05:00
Majorization theoretical approach to entanglement enhancement via local filtration
arXiv:2312.02066v2 Announce Type: replace Abstract: From the perspective of majorization theory, we study how to enhance the entanglement of a two-mode squeezed vacuum (TMSV) state by using local filtration operations. We present several schemes achieving entanglement enhancement with photon addition and subtraction, and then consider filtration as a general probabilistic procedure consisting in acting with local (non-unitary) operators on each mode. From this, we identify a sufficient set of two conditions for these filtration operators to successfully enhance the entanglement of a TMSV state, namely the operators must be Fock-orthogonal (i.e., preserving the orthogonality of Fock states) and Fock-amplifying (i.e., giving larger amplitudes to larger Fock states). Our results notably prove that ideal photon addition, subtraction, and any concatenation thereof always enhance the entanglement of a TMSV state in the sense of majorization theory. We further investigate the case of realistic photon addition (subtraction) and are able to upper bound the distance between a realistic photon-added (-subtracted) TMSV state and a nearby state that is provably more entangled than the TMSV, thus extending entanglement enhancement to practical schemes via the use of a notion of approximate majorization. Finally, we consider the state resulting from $k$-photon addition (on each of the two modes) on a TMSV state. We prove analytically that the state corresponding to $k=1$ majorizes any state corresponding to $2\leq k \leq 8$ and we conjecture the validity of the statement for all $k\geq 9$.
https://arxiv.org/abs/2312.02066
Academic Papers
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c048ff987a649fd71d22402590d7f1f4d467e03fc15ab16807407c697233858b
2026-01-23T00:00:00-05:00
Classical capacity of quantum non-Gaussian attenuator and amplifier channels
arXiv:2312.15623v2 Announce Type: replace Abstract: We consider a quantum bosonic channel that couples the input mode via a beam splitter or two-mode squeezer to an environmental mode that is prepared in an arbitrary state. We investigate the classical capacity of this channel, which we call a non-Gaussian attenuator or amplifier channel. If the environment state is thermal, we of course recover a Gaussian phase-covariant channel whose classical capacity is well known. Otherwise, we derive both a lower and an upper bound to the classical capacity of the channel, drawing inspiration from the classical treatment of the capacity of non-Gaussian additive-noise channels. We show that the lower bound to the capacity is always achievable and give examples where the non-Gaussianity of the channel can be exploited so that the communication rate beats the capacity of the Gaussian-equivalent channel (i.e., the channel where the environment state is replaced by a Gaussian state with the same covariance matrix). Finally, our upper bound leads us to formulate and investigate conjectures on the input state that minimizes the output entropy of non-Gaussian attenuator or amplifier channels. Solving these conjectures would be a main step towards accessing the capacity of a large class of non-Gaussian bosonic channels.
https://arxiv.org/abs/2312.15623
Academic Papers
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b9148e283d2ee9de64dad5c4324989e389611cb9527daf4bda727144c637ce5b
2026-01-23T00:00:00-05:00
Parallel Logical Measurements via Quantum Code Surgery
arXiv:2503.05003v3 Announce Type: replace Abstract: Quantum code surgery is a flexible and low overhead technique for performing logical measurements on quantum error-correcting codes, which generalises lattice surgery. In this work, we present a code surgery scheme, applicable to any qubit stabiliser low-density parity check (LDPC) code, that fault-tolerantly measures many logical Pauli operators in parallel. For a collection of logically disjoint Pauli product measurements supported on $t$ logical qubits, our scheme uses $O\big(t \omega (\log t + \log^3\omega)\big)$ ancilla qubits, where $\omega \geq d$ is the maximum weight of the single logical Pauli representatives involved in the measurements, and $d$ is the code distance. This is all done in time $O(d)$ independent of $t$. Our proposed scheme preserves both the LDPC property and the fault-distance of the original code, without requiring ancillary logical codeblocks which may be costly to prepare. This addresses a shortcoming of several recently introduced surgery schemes which can only be applied to measure a limited number of logical operators in parallel if they overlap on data qubits.
https://arxiv.org/abs/2503.05003
Academic Papers
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e9d954eb681f91f497a8038575b4a8a781cb483dcb16932a89b028c5a1747099
2026-01-23T00:00:00-05:00
Variational Perturbation Theory in Open Quantum Systems for Efficient Steady State Computation
arXiv:2504.00085v2 Announce Type: replace Abstract: Determining the steady state of an open quantum system is crucial for characterizing quantum devices and studying various physical phenomena. Often, computing a single steady state is insufficient, and it is necessary to explore its dependence on multiple external parameters. In such cases, calculating the steady state independently for each combination of parameters quickly becomes intractable. Perturbation theory (PT) can mitigate this challenge by expanding steady states around reference parameters, minimizing redundant computations across neighboring parameter values. However, PT has two significant limitations: it relies on the pseudo-inverse -- a numerically costly operation -- and has a limited radius of convergence. In this work, we remove both of these roadblocks. First, we introduce a variational perturbation theory (VPT) and its multipoint generalization that significantly extends the radius of convergence even in the presence of non-analytic effects such as dissipative phase transitions. Then, we develop two numerical strategies that eliminate the need to compute pseudo-inverses. The first relies on a single LU decomposition to efficiently construct the steady state within the convergence region, while the second reformulates VPT as a Krylov space recycling problem and uses preconditioned iterative methods. We benchmark these approaches across various models, demonstrating their broad applicability and significant improvements over standard PT.
https://arxiv.org/abs/2504.00085
Academic Papers
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d675c41d9fd30fa16dc41449ae2d12d3b3e818047ec4836d10790b9bd11a9a07
2026-01-23T00:00:00-05:00
Entropy-based analysis of single-qubit Otto and Carnot heat engines
arXiv:2505.01567v2 Announce Type: replace Abstract: From an entropy-based formulation of the first law of thermodynamics in the quantum regime, we investigate the performance of Otto-like and Carnot-like engines for a single-qubit working medium. Within this framework, the first law includes an additional contribution -- coherence work -- that quantifies the energetic cost of deviating the quantum trajectory from its natural unitary evolution. We focus on the efficiency of the heat-to-coherence work conversion and show that the Carnot cycle achieves the classical Carnot efficiency, while the performance of the Otto cycle is upper-bounded by the Carnot efficiency corresponding to the extreme temperatures of the cycle. We identify entropy generation during the isochoric stages as the key source of irreversibility limiting the Otto cycle's efficiency.
https://arxiv.org/abs/2505.01567
Academic Papers
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dc8af30ae32c18e4bbd83589bb91e7ed018839fa74d6e2af792710e92aea6cd0
2026-01-23T00:00:00-05:00
Gradients, parallelism, and variance of quantum estimates
arXiv:2509.11214v2 Announce Type: replace Abstract: Computation of observables and their gradients on near-term quantum hardware is a central aspect of any quantum algorithm. In this work, we first review standard approaches to the estimation of observables with and without quantum amplitude estimation for both cost functions and gradients, discuss sampling problems, and analyze variance propagation on quantum circuits with and without Linear Combination of Unitaries (LCU). Afterwards, we systematically analyze the standard approaches to gradient computation with LCU circuits. Finally, we develop a LCU gradient framework for the most general gradients based on n-qubit gates and for time-dependent quantum control gradient, analyze the convergence behaviour of the circuit estimators, and provide detailed circuit representations of both for near-term and fault-tolerant hardware.
https://arxiv.org/abs/2509.11214
Academic Papers
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dcb597003e933a62b24911a3e6e506789b4020a5f3c3c7c3821700f26357999f
2026-01-23T00:00:00-05:00
Triple-Tone Microwave Control for Sensitivity Optimization in Compact Ensemble Nitrogen-Vacancy Magnetometers
arXiv:2510.00913v3 Announce Type: replace Abstract: Ensembles of nitrogen-vacancy (NV) centers in diamond are a well-established platform for quantum magnetometry under ambient conditions. One challenge arises from the hyperfine structure of the NV, which, for the common $^{14}$N isotope, results in a threefold reduction of contrast and thus sensitivity. By addressing each of the NV hyperfine transitions individually, triple-tone microwave (MW) control can mitigate this sensitivity loss. Here, we experimentally and theoretically investigate the regimes in which triple-tone excitation offers an advantage over standard single-tone MW control for two DC magnetometry protocols: pulsed optically detected magnetic resonance (ODMR) and Ramsey interferometry. We validate a master equation model of the NV dynamics against ensemble NV measurements, and use the model to explore triple-tone vs single-tone sensitivity for different MW powers and NV dephasing rates. For pulsed ODMR, triple-tone driving improves sensitivity by up to a factor of three in the low-dephasing regime, with diminishing gains when dephasing rates approach the hyperfine splitting. In contrast, for Ramsey interferometry, triple-tone excitation only improves sensitivity if MW power is limited. Our results delineate the operating regimes where triple-tone control provides a practical strategy for enhancing NV ensemble magnetometry in portable and power-limited sensors.
https://arxiv.org/abs/2510.00913
Academic Papers
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33982fe1d01e776aa3c92962c8bc417d96b78194c640ee5bb171454dd593cb12
2026-01-23T00:00:00-05:00
Non-stabilizerness in quantum-enhanced metrological protocols
arXiv:2510.01380v2 Announce Type: replace Abstract: Non-stabilizerness (colloquially "magic") characterizes genuinely quantum (beyond-Clifford) operations necessary for preparation of quantum states, and can be measured by stabilizer R\'enyi entropy (SRE). For permutationally symmetric states, we show that the SRE depends, for sufficiently large systems, only on a constant number of expectation values of collective spin operators. This compact description is leveraged for analysis of spin-squeezing protocols, which inherently generate non-stabilizerness. Under one-axis twisting (OAT), the generation of optimal squeezing is accompanied by a logarithmic divergence of SRE with system system size. Continued time evolution under OAT produces metrologically useful "kitten" states-superpositions of rotated GHZ states-that feature many-body Bell correlations but exhibit a smaller, system-size-independent SRE that decreases with increasing Bell-correlation strength. Our results reveal connections between non-stabilizerness, multipartite correlations, and quantum metrology, and provide a practical route to quantify non-stabilizerness in experiments for precision sensing.
https://arxiv.org/abs/2510.01380
Academic Papers
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71bad618ae023ba98f664806b744d7ff4190d0856b1dfaff79327971c44cd3f5
2026-01-23T00:00:00-05:00
Verifiable blind observable estimation
arXiv:2510.08548v2 Announce Type: replace Abstract: Cryptographic verification is essential for establishing trust in quantum-computing-as-a-service. However, a fundamental gap exists in the current verification landscape: existing efficient protocols are largely restricted to decision problems where correctness is boosted by classical majority voting. This excludes observable estimation, the statistical task underpinning nearly all near-term quantum advantage applications. For such tasks, current verification techniques face a prohibitive trade-off: either weak security guarantees or massive space overhead that exceeds the capacity of near-term hardware. To resolve this, we introduce the Secure Delegated Observable Estimation (SDOE) ideal resource, the first formal cryptographic framework for trustworthy expectation-value estimation within Abstract Cryptography. We then present the Verifiable Blind Observable Estimation (VBOE) protocol, which efficiently constructs this resource. VBOE circumvents the limitations inherent in prior methodologies by enabling the sequential collection of samples with negligible security error, requiring zero extra qubit overhead. By directly averaging computation rounds in classical post-processing, our protocol provides the only known path to rigorous, composable verification for the most common class of near-term quantum-classical hybrid algorithms. This work bridges foundational cryptographic theory with practical quantum tasks, enabling the certification of quantum utility on current and near-future devices.
https://arxiv.org/abs/2510.08548
Academic Papers
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f1424c92868c7145d23f84b6140b04396a9e722a71c94e0e3dcaeba57ce59b5b
2026-01-23T00:00:00-05:00
Quantum Energy Teleportation under Equilibrium and Nonequilibrium Environments
arXiv:2511.01518v2 Announce Type: replace Abstract: Quantum energy teleportation (QET), implemented via local operations and classical communication, enables carrier-free energy transfer by exploiting quantum resources. While QET has been extensively studied theoretically and validated experimentally in various quantum platforms, enhancing energy output for mixed initial states, as the system inevitably interacts with environments, remains a significant challenge. In this work, we study QET performance in a two-qubit system coupled to equilibrium or nonequilibrium reservoirs. We derive an analytical expression for the energy output in terms of the system Hamiltonian eigenstates, enabling analysis of energy output for mixed states. Using the Redfield master equation, we systematically examine the effects of qubit detuning, nonequilibrium temperature difference, and nonequilibrium chemical potential difference on the energy output. We find that the energy output for mixed states often follows that of the eigenstate with the highest population, and that nonequilibrium environments can enhance the energy output in certain parameter regimes.
https://arxiv.org/abs/2511.01518
Academic Papers
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a2cb90741b1cda20abe81308f50a36aec0f479434b44072d285faba9937ba3ca
2026-01-23T00:00:00-05:00
Multiparameter estimation for the superresolution of two incoherent sources
arXiv:2601.14876v2 Announce Type: replace Abstract: We experimentally demonstrate the simultaneous estimation of the three parameters characterizing a pair of incoherent optical sources in the sub-Rayleigh regime, enabling super-resolved scene characterization. Using spatial-mode demultiplexing (SPADE) with two demultiplexers--one deliberately shifted--we determine separations well below the diffraction limit and achieve sensitive joint estimation of separation, centroid, and relative brightness over a broad range of scene configurations in a single experimental setting. We benchmark our performance using Fisher-information-based Cram\'er-Rao bounds, and discuss the corresponding quantum limits. We investigate two complementary scenarios: a realistic case with slightly non-identical sources, and an idealized case of indistinguishable sources.
https://arxiv.org/abs/2601.14876
Academic Papers
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17246abe9f1d1d9c608c6efce28fa1b4c495f6d7e82e599d2407f592088635de
2026-01-23T00:00:00-05:00
Duality between open systems and closed bilayer systems: Thermofield double states as quantum many-body scars
arXiv:2304.03155v4 Announce Type: replace-cross Abstract: We establish a duality between open many-body systems governed by the Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) equation and satisfying the detailed balance condition on the one side, and closed bilayer systems with a self-adjoint Hamiltonian on the other side. Under this duality, the identity operator on the open system side maps to a quantum many-body scar of the dual Hamiltonian $\mathcal H$. This scar eigenstate has a form of a thermofield double state for a single-body conserved quantity entering the detailed balance conditions. A remarkable feature of this thermofield scar is a tunable single-layer entanglement entropy controlled by the reservoir temperature on the open system side. Further, we identify broad classes of many-body open systems with nontrivial explicit eigen operators $Q$ of the Lindbladian superoperator. The expectation values of the corresponding observables exhibit a simple exponential decay, $\langle Q\rangle_t=e^{-\Gamma t} \langle Q \rangle_0$, irrespectively of the initial state. Under the above duality, these eigen operators give rise to additional (towers of) scars. Finally, we point out that more general superoperators (not necessarily of the GKSL form) can be mapped to self-adjoint Hamiltonians of bilayer systems harbouring scars, and provide an example thereof.
https://arxiv.org/abs/2304.03155
Academic Papers
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6d7ccc31d66db1f4f48e3bd946a391e69c4f2e07844d2891304e4169cedc9142
2026-01-23T00:00:00-05:00
Vestigial Gapless Boson Density Wave Emerging between $\nu = 1/2$ Fractional Chern Insulator and Finite-Momentum Supersolid
arXiv:2408.07111v2 Announce Type: replace-cross Abstract: The roton-triggered charge-density-wave (CDW)is widely studied in fractional quantum Hall (FQH) and fractional Chern insulator (FCI) systems, and there also exist field theoretical and numerical realizations of continuous transition from FCI to superfluid (SF). However, the theory and numerical explorations of the transition between FCI and supersolid (SS) are still lacking. In this work, we study the topological flat-band lattice models with $\nu$ = 1/2 hard-core bosons, where the previous studies have discovered the existence of FCI states and possible direct FCI-SS transitions. While the FCI is robust, we find the direct FCI-SS transition is absent, and there exist more intriguing scenarios. In the case of checkerboard lattice, we find an intermediate gapless CDW state without SF, sandwiched between FCI and SS. This novel state is triggered by the roton instability in FCI and it further continuously brings about the intertwined finite-momentum SF fluctuation when the CDW order is strong enough, eventually transiting into an unconventional finite-momentum SS state. The intermediate gapless CDW state is a vestige from the SS state, since the increasing quantum fluctuation melts only the Larkin-Ovchinnikov-type SF order in SS but its (secondary) product -- the CDW order -- survives. On honeycomb lattice, we find no evidence of SS, but discover an interesting sequence of FCI-Solid I-Solid II transitions, with both solids incompressible. Moreover, in contrast to previous single-roton condensation, this sequence of FCI-Solid I-Solid II transitions is triggered by the softening of multi-roton modes in FCI. Considering the intertwined wave vectors of the CDW orders, Solid I is a vestige of Solid II. Our work provides new horizon not only for the quantum phase transitions in FCI but also for the intertwined orders and gapless states in bosonic systems, which will inspire future studies.
https://arxiv.org/abs/2408.07111
Academic Papers
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d125f912e66cfa8a1e71c87067de7eb4883e3b93d4a9ae3c2ffc694119f9fb74
2026-01-23T00:00:00-05:00
Electrical Interconnects for Silicon Spin Qubits
arXiv:2411.01366v2 Announce Type: replace-cross Abstract: Scalable spin qubit devices will likely require long-range qubit interconnects. We propose to create such an interconnect with a resistive topgate. The topgate is positively biased, to form a channel between the two dots; an end-to-end voltage difference across the nanowire results in an electric field that propels the electron from source dot to target dot. The electron is momentum-incoherent, but not necessarily spin-incoherent; we evaluate threats to spin coherence due to spin-orbit coupling, valley physics, and nuclear spin impurities. We find that spin-orbit coupling is the dominant threat, but momentum-space motional narrowing due to frequent scattering partially protects the electron, resulting in characteristic decoherence lengths ~15 mm for plausible parameters.
https://arxiv.org/abs/2411.01366
Academic Papers
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cb0b1b7b6d52efb83ad00907e20e2fff8bf65a75ee1ab637946092a259aa90ac
2026-01-23T00:00:00-05:00
Fusion Dynamics of Majorana Zero Modes
arXiv:2503.09800v2 Announce Type: replace-cross Abstract: Braiding and fusion of Majorana zero modes are key elements of any future topological Majorana-based quantum computer. Here, we investigate the fusion dynamics of Majorana zero modes in the spinless Kitaev model, as well as in a spinful model describing magnet-superconductor hybrid structures. We consider various scenarios allowing us to reproduce the fusion rules of the Ising anyon model. Particular emphasis is given to the charge of the fermion obtained after fusing two Majorana zero modes: as long as it remains on the superconductor, charge quantization is absent. When moving the fermion to a non-superconducting region, such as a quantum dot, nearly-quantized charge can be measured. Our findings confirm for both platforms that fusion dynamics of Majorana zero modes can indeed be used for the readout of Majorana qubits.
https://arxiv.org/abs/2503.09800
Academic Papers
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4a568ed19b61ce8f8f2e8b513a32d8accbfa1bd80b8a5664e4c8e0d2e0bca939
2026-01-23T00:00:00-05:00
Bose-Einstein condensation in exotic lattice geometries
arXiv:2505.16885v2 Announce Type: replace-cross Abstract: Modern quantum engineering techniques allow for synthesizing quantum systems in exotic lattice geometries, from self-similar fractal networks to negatively curved hyperbolic graphs. We demonstrate that these structures profoundly reshape Bose-Einstein condensation. Fractal lattices dramatically lower the condensation temperature and enhance condensation fluctuations. In a Sierpi\'nski carpet, quasi-degeneracies in the tight-binding spectrum fragment the condensate. Hyperbolic lattices, on the other hand, exhibit condensation features similar to regular three-dimensional lattices, despite their embedding in only two dimensions: The critical temperature increases as the system grows, and the temperature-dependence of the condensate fraction follows the same power-law as for cubic lattices. We explain these similarities through the similarity of the densities of state at low energies. When strong repulsive interactions are included, the gas enters a Mott insulating state. Using a multi-site Gutzwiller approach as well as a simple strong-coupling expansion, for the Sierpi\'nski triangle we find a smooth interpolation between the characteristic insulating lobes of one-dimensional and two-dimensional systems. Our findings establish lattice geometry as a powerful tuning knob for quantum phase phenomena and pave the way for experimental exploration in photonic waveguide arrays and Rydberg-atom tweezer arrays.
https://arxiv.org/abs/2505.16885
Academic Papers
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61e41163577281fafafbff37239b734117206e5696b5c81edc617e067204b5ee
2026-01-23T00:00:00-05:00
Non-Abelian Statistics for Bosonic Symmetry-Protected Topological Phases
arXiv:2508.12444v4 Announce Type: replace-cross Abstract: Symmetry-protected non-Abelian (SPNA) statistics opens new frontiers in quantum statistics and enriches the schemes for topological quantum computing. In this work, we propose a new paradigm of SPNA statistics in one-dimensional correlated bosonic symmetry-protected topological (SPT) phases and uncover exotic universal features from a systematic investigation. In particular, we show that for generic bosonic SPT phases described by real Hamiltonians, the SPNA statistics of topological zero modes fall into two distinct classes. The first class exhibits conventional braiding of hard-core bosonic zero modes. Furthermore, we discover a second class of unconventional braiding statistics characterized by a nonlinear transformation, featuring a fractionalization of the first class and reminiscent of the non-Abelian statistics of symmetry-protected Majorana pairs. The two distinct classes of statistics have topological origin in classifying non-Abelian Berry phases for braiding processes of real-Hamiltonian systems, distinguished by whether the holonomy involves a reflection operation. To illustrate, we focus on a specific bosonic SPT phase with particle-hole symmetry, and demonstrate that both classes of braiding statistics can be feasibly realized in a tri-junction with and without the aid of a controlled defect, respectively. Analytic and numerical results are given. We demonstrate how to encode logical qubits and implement both single- and two-qubit gates using the two classes of SPNA statistics. Finally, we propose feasible experimental schemes to observe these predictions and identify the parameter regimes for the high-fidelity braiding, paving the way for the experimental observation of our results in the near future.
https://arxiv.org/abs/2508.12444
Academic Papers
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e49c14f12370000add8a7f8c2f70df8584b041a6f95f929c90efa7d9705a5f46
2026-01-23T05:00:22+00:00
Trump’s tariff ‘shock regime’ tests Wall Street’s mettle
US president backed off his threat of new duties on European economies after market tumult
https://www.ft.com/content/cb1a8211-ac60-4cb2-b68f-955f3d0f98f5
Business & Finance
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af9a0b1a22d3b26874b92cdeb37ed90d809722ac9d9ec61e5aee7a0aa7ed5407
2026-01-23T05:00:22+00:00
‘Waiting for the king’: how Trump dominated Davos
Elite business forum draws record attendance but US president’s foreign policy fuels tension and walkouts
https://www.ft.com/content/49286969-ab39-4cbd-bb18-f563cc2eb31b
Business & Finance
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ad83287bafcccaad65c6e7ff5a0e6e300b0f5b7fa45fa56356e3e63274fc8e27
2026-01-23T07:15:25+00:00
Donald Trump withdraws Mark Carney’s invitation to join ‘Board of Peace’
Move comes after Canadian prime minister took aim at US president in Davos speech
https://www.ft.com/content/15d88de2-07e9-42c6-8001-afbc3a53b828
Business & Finance
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39e3ac9e40f6136c1cbd06576bb32c6ec9811254d5b40ebb47568f3c68ec3cda
2026-01-23T05:00:12+00:00
Greenland has had enough of Trump
Anxiety and patriotism swirl as details of a ‘future deal’ touted by US president trickle out
https://www.ft.com/content/726fd41e-a9d9-43ac-afaf-cc7257b1a387
Business & Finance
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57c87c023baaea64eaa11b0a131a919f45ce90eab1e551070d07bc955e7235d8
2026-01-23T12:56:24+00:00
Mark Rutte, Europe’s Trump whisperer-in-chief
The Nato secretary-general is happy to use flattery in order to get things done
https://www.ft.com/content/fe1aad9e-3bd0-48e0-98fa-33fab2fb91dd
Business & Finance
https://www.ft.com/__ori…0&fit=scale-down
e3b53be54d865f1bacf8978f385c47e7afc59b3abc378c9b8c0974729b571320
2026-01-23T05:00:12+00:00
What business should be thinking about post-Davos
Ignoring the upside can be as dangerous as discounting the downside
https://www.ft.com/content/deb0b172-0e47-410c-b458-d4319877bcd6
Business & Finance
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17234e70ad30e06c6851cc93df6318d4560aef63a0501b587b1e21d079dc20c0
2026-01-23T05:00:22+00:00
Revolut scraps US merger plans in favour of push for standalone licence
UK-headquartered fintech had hoped to secure banking charter through buying an American lender
https://www.ft.com/content/908e261f-2b78-4798-8aa2-aff2e828d31a
Business & Finance
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66b914fb4958dc5054d553be482ee4716a269c632aa7318344c29b95fc0273dd
2026-01-22T23:08:07+00:00
Trump sues JPMorgan and CEO Dimon for $5bn over debanking
US president claims lender unfairly closed his accounts for political reasons
https://www.ft.com/content/da3b880c-fcab-47d8-a40c-9e6755616e94
Business & Finance
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00210074cccb488f836e87716ddd89e70e8d06298061b7680a667120cc4accd0
2026-01-22T23:44:33+00:00
Flatter Trump or fight him? Smart billionaires do both
Good relations with the US commander-in-chief are more than a nice-to-have
https://www.ft.com/content/b0f16c20-5b82-40ee-866e-11131df0d229
Business & Finance
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e3745809b432730d328605f41afd2bad57834445c2a4d4eef12db60a11ada6ae
2026-01-23T11:49:14+00:00
Shares in Czech ammunition group surge 29% on stock market debut
Performance of Czechoslovak Group underlines strong investor demand for defence companies
https://www.ft.com/content/9796dc0a-6d51-4ce4-b67a-0c63ca3adf8e
Business & Finance
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c06583f6f4cf3ae7eaccefe312d98f3198011f3cf8dc99395f907a1319061010
2026-01-23T09:26:52+00:00
Trump sends US armada towards Iran ‘just in case’
Naval forces dispatched to stop Tehran restarting nuclear programme or executing protesters, US president says
https://www.ft.com/content/04190ed3-7631-4c75-8d16-1dc3dc5ded6f
Business & Finance
https://www.ft.com/__ori…0&fit=scale-down
19c4a939c3ce0e751999019320fd7267e44d89afeacf52049f2fdb91c20ce8fc
2026-01-23T12:21:00+00:00
The case for a U.S. bear market was building even before Trump antagonized overseas investors
There are two important measures that point to a downturn for stocks, according to Longview Economics.
https://www.marketwatch.com/story/the-case-for-a-u-s-bear-market-was-already-building-before-trump-upset-foreign-investors-1d4399ee?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-71968355
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2026-01-23T12:20:00+00:00
Gold is approaching $5,000, and ‘unavoidable uncertainty’ means it could go higher
RBC’s head of commodities says there could be paths even higher for gold in a “real risk-off scenario.”
https://www.marketwatch.com/story/gold-is-approaching-5-000-and-unavoidable-uncertainty-means-it-could-go-higher-ec8480a4?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-25135913
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2026-01-23T12:15:00+00:00
‘It’s my money’: My $800K inheritance is paying for a $1.6 million house. Shouldn’t I decide where my husband and I live?
‘My husband and I have been together for 25 years. We have two children’
https://www.marketwatch.com/story/its-my-money-my-800k-inheritance-is-paying-for-a-1-6-million-house-shouldnt-i-decide-where-my-husband-and-i-live-995dbd0c?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-02241249
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2026-01-23T11:53:00+00:00
Nvidia’s on-and-off China relationship appears to be on again
The on-and-off saga involving Nvidia and China appears to be back on again, after a report that China’s government has given the go-ahead to big companies including Alibaba to buy the U.S. semiconductor maker’s chips.
https://www.marketwatch.com/story/nvidias-on-and-off-china-relationship-appears-to-be-on-again-f7bd6379?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-82451831
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2026-01-23T10:50:00+00:00
Natural gas prices have overshot as deep freeze hits the U.S., says Goldman
Goldman Sachs thinks the current natural gas price reflects a temporary imbalance and should eventually correct.
https://www.marketwatch.com/story/natural-gas-prices-have-overshot-as-deep-freeze-hits-the-u-s-says-goldman-a76e5a82?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-01934734
32a460643940dd90eaab534e39889ca02432a1c37100f5319aeb60e77db5911f
2026-01-23T10:15:00+00:00
I’m inheriting $250K. Will paying off my student loans and credit-card debt hurt my credit score?
“I will get $250,000 from the proceeds of the sale of a family home.”
https://www.marketwatch.com/story/im-inheriting-250k-will-paying-off-my-student-loans-and-credit-card-debt-hurt-my-credit-score-4679d9ab?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-59939296
0d9e3825151f1d81d0cfffe775c83c11e79ca8edef82d7e13f0d6e77886b4343
2026-01-23T10:00:00+00:00
A year later, ‘General Hospital’ star Cameron Mathison talks about losing his home in L.A. fires
“General Hospital” star Cameron Mathison shared a heartbreaking video of the devastation caused when the blaze ripped through his home last year.
https://www.marketwatch.com/story/a-year-later-general-hospital-star-cameron-mathison-talks-about-losing-his-home-in-l-a-fires-32d328aa?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-38686002
52a0e3eb0b675b7d5060e93d6e6cf2fb859f9f6ed040767865610a983f504a51
2026-01-23T09:29:00+00:00
Amazon reportedly to announce second wave of job cuts
Amazon.com workers are bracing for another round of massive job cuts, with the company reportedly expected to announce those cuts as soon as next week.
https://www.marketwatch.com/story/amazon-reportedly-to-announce-second-wave-of-job-cuts-3b0e2dee?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-79710430
007d1041362e85e34a3274620056b7321e5ba8627e3456df050e2a460c685c70
2026-01-23T09:28:00+00:00
It’s a hit: Prescriptions for Wegovy weight-loss drug pill surge
The oral weight-loss drug introduced by Novo Nordisk this year in the U.S. is quickly being adopted.
https://www.marketwatch.com/story/its-a-hit-wegovy-weight-loss-drug-pill-prescriptions-surge-acdcf466?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-54628327
0b858462ea7192e3a12e13f44e3aef883a910b6ce4fc8670ba6762df5b327a25
2026-01-23T08:00:00+00:00
My husband’s kids didn’t even show up for his heart surgery. So why is he leaving them his $1 million life insurance?
“Both of us were widowed. We are in our late 60s and retired.”
https://www.marketwatch.com/story/i-am-resentful-my-second-husbands-kids-treat-him-like-dirt-so-why-is-he-leaving-them-his-1-million-life-insurance-8fe0f2ae?mod=mw_rss_topstories
Business & Finance
https://images.mktw.net/im-51889417
10002ece555598f71d724c6b8241036a9a8a91e8b623f9b99628947a23ad2aea
2026-01-23T12:48:57+00:00
Wall Street braced for a private credit meltdown. The risk of one is rising
Private credit is expected to grow from $3.4 trillion in 2025 to an estimated $4.9 trillion by 2029. Wall Street is starting to raise alarms about the risks.
https://www.cnbc.com/2026/01/23/wall-street-private-credit-risk-rising.html
Business & Finance
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e69a89e18c4ccf186242eb8613a7743e95e35683e2a2e2fc6f3f0e07e1f5616c
2026-01-23T12:50:24+00:00
What obesity drugmakers see next in the market: More pills, easier access and drug combinations
CNBC spoke to executives from Eli Lilly, Novo Nordisk, Pfizer and other drugmakers at the annual JPMorgan Healthcare Conference in San Francisco.
https://www.cnbc.com/2026/01/23/weight-loss-glp-1-drugs-next-steps-for-eli-lilly-novo-nordisk-pfizer.html
Business & Finance
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2026-01-23T12:54:41+00:00
Trump withdraws 'Board of Peace' invitation to Carney in widening rift with Canada
Trump said he has withdrawn the invitation to Canada to join the new Board of Peace, days after Carney warned against economic coercion by superpowers.
https://www.cnbc.com/2026/01/23/trump-withdraws-board-of-peace-invitation-to-carney-in-widening-rift-with-canada.html
Business & Finance
svg
589fc43337f5c6a987d83a0807c2b7f8515e6a60a284c8aed1f5c9defdfc1f88
2026-01-23T12:50:56+00:00
Capital One is buying startup Brex for $5.15 billion in credit card firm's latest deal
Capital One's acquisition of Brex is the latest deal under Rich Fairbank, a rare founder-CEO of a major U.S. bank, after its Discover Financial acquisition.
https://www.cnbc.com/2026/01/22/capital-one-is-buying-startup-brex-for-5point15-billion-in-credit-card-firms-latest-deal.html
Business & Finance
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fdc37187f806eb873f7e6e025d22f57f4232594e14c7db017c27d003534a8700
2026-01-23T12:28:57+00:00
House passes final funding bills 8 days before shutdown, Senate now will consider
The Senate will still have to pass the measures when it returns to Washington next week.
https://www.cnbc.com/2026/01/22/government-funding-shutdown-house.html
Business & Finance
svg
f4e70836a2d6e9b0918b8d800cb4ae8f8319ea53d0419474b5cabeef2fca9e2b
2026-01-23T10:18:34+00:00
Adani group stocks plunge as U.S. SEC looks to question founder over fraud charges
The U.S. Securities and Exchange Commission is seeking permission to send summons to Gautam Adani and two others over fraud and bribery charges.
https://www.cnbc.com/2026/01/23/adani-group-shares-sec-investigation-fraud.html
Business & Finance
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12ab8c7eb69e08248ce59027ad6f3721f357e65e689d99608a7002d1a6800023
2026-01-23T12:30:04+00:00
Shares of CSG, one of the world’s fastest-growing defense firms, jump 30% on debut
Shares of Czech-based defense firm Czechoslovak Group (CSG) soared over 30% on its stock market debut on Friday.
https://www.cnbc.com/2026/01/23/csg-stock-debut-ipo-defense-amsterdam-czech.html
Business & Finance
svg
eca9d75e9d4508a09c0decf875c9c08b5a69b0e9089eac5f350f416b57ceaa98
2026-01-23T13:10:45+00:00
Airlines cancel hundreds of flights as massive winter storm sweeps across U.S.
U.S. airlines canceled flights and waived change fees for travelers as a cold snap and massive winter storm were forecast to sweep across the country.
https://www.cnbc.com/2026/01/23/winter-storm-fern-flight-cancellations.html
Business & Finance
svg
2bee8599e81bb36ec0e37556820b2097d5d1a30a142aaf4944872704aa3244ae
2026-01-23T13:44:12+00:00
How a smaller IRS, budget cuts may impact 2026 tax filing: 'Buckle your seatbelts,' one expert says
IRS staffing and budget cuts could impact the 2026 tax filing season. Here's what taxpayers need to know.
https://www.cnbc.com/2026/01/23/smaller-irs-budget-cuts-impact-2026-tax-season.html
Business & Finance
svg
6d7286db8549499d3b4b983f2e3910a3ebfd177190e169c2c16bc694321a7212
2026-01-23T12:59:16+00:00
From French drug pricing to 'loser' windmills: A rundown of who Trump criticized at Davos
U.S. President Donald Trump sharply criticized a number of current and former political leaders at the World Economic Forum in Davos.
https://www.cnbc.com/2026/01/23/trump-davos-canada-carney-france-macron-spain-china-wind.html
Business & Finance
svg
94238f42eaf8f265f8fe707b47bb6b145094ef8a0343a3e3ca5b0ab63b02c681
2026-01-23T13:19:24+00:00
Social Security has 'no bankruptcy or collapse in the cards,' economist says — but benefits may change
While surveys show Americans worry Social Security will run out of money, benefits will continue, one economist says.
https://www.cnbc.com/2026/01/23/will-social-security-run-out-is-the-wrong-question-economist-says.html
Business & Finance
svg
89751070e1d3d4c5b1913714700ce58aa2941b0a2cd609f2fd5e436d80d78b28
2026-01-23T13:18:29+00:00
Why a niche category of CRE lending is suddenly seeing record deals
C-PACE stands for commercial property assessed clean energy and is a type of financing that differs from a traditional bank loan. It's seeing explosive growth.
https://www.cnbc.com/2026/01/23/c-pace-cre-lending-record-deals.html
Business & Finance
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bc3f9687cd83040133404f729ecd5ddd5493cbbfb81e4b9af731f2b5c90f469c
2026-01-23T12:31:43+00:00
Nvidia’s Huang to visit China as AI chip sales stall
Nvidia CEO Jensen Huang plans to visit China ahead of the mid-February Lunar New Year, two people familiar with the matter told CNBC.
https://www.cnbc.com/2026/01/23/nvidia-ceo-jensen-huang-china-visit-chip-sales-restrictions.html
Business & Finance
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