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2010-11-22
Amplitude equations and fast transition to chaos in rings of coupled oscillators
We study the coupling induced destabilization in an array of identical oscillators coupled in a ring structure where the number of oscillators in the ring is large. The coupling structure includes different types of interactions with several next neighbors. We derive an amplitude equation of Ginzburg-Landau type, which...
1011.4786v2
2010-12-07
Composite Higgs Boson Pair Production at the LHC
The measurement of the trilinear and quartic Higgs self-couplings is necessary for the reconstruction of the Higgs potential. This way the Higgs mechanism as the origin of electroweak symmetry breaking can be tested. The couplings are accessible in multi-Higgs production processes at the LHC. In this paper we investiga...
1012.1562v1
2010-12-11
Nonminimal curvature-matter coupled wormholes with matter satisfying the null energy condition
Recently, exact solutions of wormhole geometries supported by a nonminimal curvature-matter coupling were found, where the nonminimal coupling minimizes the violation of the null energy condition of normal matter at the throat. In this brief report, we present a solution where normal matter satisfies the energy conditi...
1012.2443v1
2010-12-21
Kondo effects and shot noise enhancement in a laterally coupled double quantum dot
The spin and orbital Kondo effects and the related shot noise for a laterally coupled double quantum dot are studied taking account of coherent indirect coupling via a reservoir. We calculate the linear conductance and shot noise for various charge states to distinguish between the spin and orbital Kondo effects. We fi...
1012.4838v1
2010-12-29
The bulk transition of many-flavour QCD and the search for a UVFP at strong coupling
We explore the nature of the bulk transition observed at strong coupling in the SU(3) gauge theory with Nf=12 fermions in the fundamental representation. The transition separates a weak coupling chirally symmetric phase from a strong coupling chirally broken phase and is compatible with the scenario where conformality ...
1012.5971v1
2011-01-04
The quantum description and stimulated emission radiation of coupled metamaterials
In recent years, there has been increasing interest in studying the quantum characteristics in plasmonic metamaterials. By using the Hamiltonian combined with second quantization, we have investigated the basic excitation of the coupled metamaterials and presented a quantum description of them. The interaction between ...
1101.0733v1
2011-01-11
Analog of Electromagnetically Induced Transparency Effect for Two Nano/Micro-mechanical Resonators Coupled With Spin Ensemble
We study a hybrid nano-mechanical system coupled to a spin ensemble as a quantum simulator to favor a quantum interference effect, the electromagnetically induced transparency (EIT). This system consists of two nano-mechanical resonators (NAMRs), each of which coupled to a nuclear spin ensemble. It could be regarded as...
1101.2115v1
2011-01-12
Dynamics of a driven spin coupled to an antiferromagnetic spin bath
We study the behavior of the Rabi oscillations of a driven central spin (qubit) coupled to an antiferromagnetic spin bath (environment). It is found that the decoherence behavior of the central spin depends on the detuning, driving strength, the qubit-bath coupling and an important factor, associated with the number of...
1101.2386v1
2011-01-27
Interfacial thermal transport in atomic junctions
We study ballistic interfacial thermal transport across atomic junctions. Exact expressions for phonon transmission coefficients are derived for thermal transport in one-junction and two-junction chains, and verified by numerical calculation based on a nonequilibrium Green's function method. For a single-junction case,...
1101.5225v1
2011-02-07
Ab initio coupled-cluster theory for open-shell nuclei
We develop a new method to describe properties of truly open-shell nuclei. This method is based on single-reference coupled-cluster theory and the equation-of-motion method with extensions to nuclei with $A\pm 2$ nucleons outside a closed shell. We perform proof-of-principle calculations for the ground states of the he...
1102.1293v1
2011-02-15
Improvement of BP-Based CDMA Multiuser Detection by Spatial Coupling
Kudekar et al. proved that the belief-propagation (BP) threshold for low-density parity-check codes can be boosted up to the maximum-a-posteriori (MAP) threshold by spatial coupling. In this paper, spatial coupling is applied to randomly-spread code-division multiple-access (CDMA) systems in order to improve the perfor...
1102.3061v3
2011-02-19
Strong coupling of two interacting excitons confined in a nanocavity-quantum-dot system
We present a study of the strong coupling between radiation and matter, considering a system of two quantum dots, which are in mutual interaction and interacting with a single mode of light confined in a semiconductor nanocavity. We take into account dissipative mechanisms such as the escape of the cavity photons, deca...
1102.4007v2
2011-03-03
Yes-go cross-couplings in collections of tensor fields with mixed symmetries of the type (3,1) and (2,2)
Under the hypotheses of analyticity, locality, Lorentz covariance, and Poincare invariance of the deformations, combined with the requirement that the interaction vertices contain at most two space-time derivatives of the fields, we investigate the consistent cross-couplings between two collections of tensor fields wit...
1103.0634v1
2011-03-03
Quantum communication through Jaynes-Cummings-Hubbard arrays
We study the dynamics of an one dimensional array of Jaynes-Cummings-Hubbard system of arbitrary number of coupled cavities, each containing a two level atom that interacts with a field mode. In particular, we consider propagation of a single excitation quantum state for two different couplings of the photonic modes of...
1103.0640v1
2011-03-07
Stable magnetostructural coupling with tunable magnetoresponsive effects in hexagonal phase-transition ferromagnets
The magnetostructural coupling between the structural and the magnetic transition plays a crucial role in magnetoresponsive effects in a martensitic-transition system. A combination of various magnetoresponsive effects based on this coupling may facilitate the multifunctional applications of a host material. Here, we d...
1103.1313v2
2011-03-11
Influence of correlations on transitive electron-phonon couplings in cuprate superconductors
We investigate a model for the CuO_2 plane of high-T_c superconductors where the charge carriers are coupled to A_{1g} and B_{1g} symmetric out-of plane vibrations of the oxygen atoms in the presence of local Hubbard correlations. The coupling is implemented via a modulation of the hopping integral and we calculate the...
1103.2320v1
2011-03-15
Limits on Anomalous Trilinear Gauge Couplings in Zgamma Events from ppbar Collisions at sqrt{s} = 1.96 TeV
Using \Zg\ candidate events collected by the CDF detector at the Tevatron Colli\der, we search for potential anomalous (non-standard-model) couplings between t\he $Z$ boson and the photon. \Zg\ couplings vanish at tree level and are heavil\y suppressed at higher orders; hence any evidence of couplings indicates new ph\...
1103.2990v2
2011-03-17
Exact mean field inference in asymmetric kinetic Ising systems
We develop an elementary mean field approach for fully asymmetric kinetic Ising models, which can be applied to a single instance of the problem. In the case of the asymmetric SK model this method gives the exact values of the local magnetizations and the exact relation between equal-time and time-delayed correlations....
1103.3433v3
2011-03-29
Scalar Decay Constant and Yukawa Coupling in Walking Gauge Theories
We propose an approach for the calculation of the yukawa coupling through the scalar decay constant and the chiral condensate in the context of the extended technicolor (ETC). We perform the nonperturbative computation of the yukawa coupling based on the improved ladder Schwinger-Dyson equation. It turns out that the y...
1103.5576v3
2011-04-04
Topological phase transitions between chiral and helical spin textures in a lattice with spin-orbit coupling and a magnetic field
We consider the combined effects of large spin-orbit couplings and a perpendicular magnetic field in a 2D honeycomb fermionic lattice. This system provides an elegant setup to generate versatile spin textures propagating along the edge of a sample. The spin-orbit coupling is shown to induce topological phase transition...
1104.0643v2
2011-04-14
Coupled magnetic-ferroelectric metal-insulator transitions in epitaxially-strained SrCoO$_{3}$ from first principles
First-principles calculations of the epitaxial-strain phase diagram of perovskite SrCoO$_{3}$ are presented. Through combination of the large spin-phonon coupling with polarization-strain coupling and coupling of the band gap to the polar distortion, both tensile and compressive epitaxial strain are seen to drive the b...
1104.2856v1
2011-04-30
Robustness of spin-coupling distributions for perfect quantum state transfer
The transmission of quantum information between different parts of a quantum computer is of fundamental importance. Spin chains have been proposed as quantum channels for transferring information. Different configurations for the spin couplings were proposed in order to optimize the transfer. As imperfections in the cr...
1105.0071v1
2011-05-04
Coupled Graphical Models and Their Thresholds
The excellent performance of convolutional low-density parity-check codes is the result of the spatial coupling of individual underlying codes across a window of growing size, but much smaller than the length of the individual codes. Remarkably, the belief-propagation threshold of the coupled ensemble is boosted to the...
1105.0785v1
2011-05-04
Interplay of couplings between antiferrodistortive, ferroelectric, and strain degrees of freedom in monodomain PbTiO$_{3}$/SrTiO$_{3}$ superlattices
We report first-principles calculations on the coupling between epitaxial strain, polarization, and oxygen octahedra rotations in monodomain (PbTiO$_{3}$)$_{n}$/(SrTiO$_{3}$)$_{n}$ superlattices. We show how the interplay between (i) the epitaxial strain and (ii) the electrostatic conditions, can be used to control the...
1105.0804v2
2011-05-06
Measuring Top Squark Interactions With The Standard Model Through Associated Production
A new particle's interactions can be measured at colliders, by observing its associated production with Standard Model particles. We focus on the case of a collider-stable right-handed top squark and study the LHC sensitivities to its couplings to the photon, Z, and the Higgs boson. Such measurements determine the top ...
1105.1332v2
2011-05-07
Enhanced Coherence of a Quantum Doublet Coupled to Tomonaga-Luttinger Liquid Leads
We use boundary field theory to describe the phases accessible to a tetrahedral qubit coupled to Josephson junction chains acting as Tomonaga-Luttinger liquid leads. We prove that, in a pertinent range of the fabrication and control parameters, an attractive finite coupling fixed point emerges due to the geometry of th...
1105.1443v2
2011-05-13
Quantitative reliability of Migdal-Eliashberg theory for strong electron-phonon coupling
We reassess the validity of Migdal-Eliashberg (ME) theory for coupled electron-phonon systems for large couplings $\lambda$. Although model calculations have found that ME theory breaks down for $\lambda\sim 0.5$, it is routinely applied for $\lambda>1$ to strong coupling superconductors. To resolve this discrepancy it...
1105.2833v3
2011-05-17
Jaynes Cummings treatment of superconducting resonators with dielectric loss due to two-level systems
We perform a quantum mechanical analysis of superconducting resonators subject to dielectric loss arising from charged two-level systems. We present numerical and analytical descriptions of the dynamics of energy decay from the resonator within the Jaynes-Cummings model. Our analysis allows us to distinguish the strong...
1105.3446v1
2011-05-20
Fluxon analogues and dark solitons in linearly coupled Bose-Einstein condensates
Two effectively one-dimensional parallel coupled Bose-Einstein condensates in the presence of external potentials are studied. The system is modelled by linearly coupled Gross-Pitaevskii equations. In particular, grey-soliton-like solutions representing analogues of superconducting Josephson fluxons as well as coupled ...
1105.4030v2
2011-05-25
Anomalous Higgs Couplings at the LHC
We discuss the impact and potential discovery of physics beyond the Standard Model, coupling to the Higgs sector, at the LHC. Using a model-independent effective Lagrangian approach, pure Higgs and Higgs-gauge operators are analyzed, and their origin in terms of tree-level exchange of unknown heavy messengers is system...
1105.5140v2
2011-06-07
Decoherence of Coupled Quantum Oscillators: Going Beyond the Caldeira-Leggett Approximation
We calculate the reduced density matrix for a system of coupled harmonic oscillators in a bosonic heat bath using the Born-Markov approximation and show that the expectation values of position and momentum evolve like classical quantities. We consider the cases where every oscillator is coupled to its own reservoir and...
1106.1371v2
2011-06-18
Evolution from BCS to BEC superfluidity in the presence of spin-orbit coupling
We discuss the evolution from BCS to BEC superfluids in the presence of spin-orbit coupling, and show that this evolution is just a crossover in the balanced case. The dependence of several thermodynamic properties, such as the chemical potential, order parameter, pressure, entropy, isothermal compressibility and spin ...
1106.3613v1
2011-06-20
Yukawa alignment from natural flavor conservation
We study the charged Higgs couplings to fermions in the "democratic" three-Higgs-doublet model, in which one doublet couples to down-type quarks, one to up-type quarks, and one to charged leptons. Flavor-changing neutral Higgs couplings are absent because the Glashow-Weinberg-Paschos condition for natural flavor conser...
1106.4039v3
2011-06-21
Percolation in Interdependent and Interconnected Networks: Abrupt Change from Second to First Order Transition
Robustness of two coupled networks system has been studied only for dependency coupling (S. Buldyrev et. al., Nature, 2010) and only for connectivity coupling (E. A. Leicht and R. M. D'Souza, arxiv:09070894). Here we study, using a percolation approach, a more realistic coupled networks system where both interdependent...
1106.4128v1
2011-06-22
Effective axial-vector coupling of gluon as an explanation to the top quark asymmetry
We explore the possibility that the large $t\bar t$ forward-backward asymmetry measured by the CDF detector at Tevatron could be due to a universal effective axial-vector coupling of gluon. Using an effective field theory approach we show model independently how such a log-enhanced coupling occurs at 1-loop level. The ...
1106.4553v3
2011-06-28
From Strong to Weak Coupling Regime in a Single GaN Microwire up to Room Temperature
Large bandgap semiconductor microwires constitute a very advantageous alternative to planar microcavities in the context of room temperature strong coupling regime between exciton and light. In this work we demonstrate that in a GaN microwire, the strong coupling regime is achieved up to room temperature with a large R...
1106.5595v2
2011-06-29
The Top Forward Backward Asymmetry with general Z ' couplings
The measurement of the top forward-backward asymmetry in $\ttbar$ production measured at the Tevatron shows deviation from the Standard Model prediction. A $ u \to t$ transition via a flavor changing $Z^{\prime}$ can explain the data. We show that left handed $t_Lu_LZ^{\prime}$ couplings can be constrained from $B_{d,s...
1106.5982v3
2011-07-05
Explaining the t-tbar asymmetry with a light axigluon
We propose an axigluon with mass between 400 and 450 GeV and flavor universal couplings to quarks to explain the Tevatron t-tbar forward-backward asymmetry. The model predicts a small negative asymmetry for t-tbar pairs with invariant mass below 450 GeV and a large positive asymmetry above 450 GeV. The asymmetry arises...
1107.0978v2
2011-07-08
Stationary entanglement in strongly coupled qubits
The dynamics of two superconducting flux qubits coupled to each other and to a common bath is discussed. We focus on the case in which the qubit-qubit coupling strength dominates over the respective qubit transition frequencies. We derive the master equation including collective effect by modeling the bath as 1D open s...
1107.1587v1
2011-07-11
Dark Matter data and constraints on quartic couplings in IDM
We analyse the thermal evolution of the Universe in the Inert Doublet Model for three regions of Dark Matter masses: low mass (4-8) GeV, medium mass (30-80) GeV and high mass (500-1000) GeV. Those three regions of DM mass exhibit different behaviour, both in the possible types of evolution and in the energy relic densi...
1107.1991v1
2011-07-21
Adaptive synchronization in delay-coupled networks of Stuart-Landau oscillators
We consider networks of delay-coupled Stuart-Landau oscillators. In these systems, the coupling phase has been found to be a crucial control parameter. By proper choice of this parameter one can switch between different synchronous oscillatory states of the network. Applying the speed-gradient method, we derive an adap...
1107.4197v1
2011-07-22
Large spin-phonon coupling and magnetically-induced phonon anisotropy in Sr$M$O$_3$ perovskites ($M$=V,Cr,Mn,Fe,Co)
First-principles calculations reveal large zone-center spin-phonon coupling and magnetically-driven phonon anisotropy in cubic perovskites Sr$M$O$_3$ ($M$=V,Cr,Mn,Fe,Co). In particular, the frequency and splitting of the polar Slater mode is found to depend strongly on magnetic ordering. The coupling is parameterized i...
1107.4405v1
2011-07-25
Spin-Orbit Coupled Bose-Einstein Condensate under Rotation
We examine the combined effects of Rashba spin-orbit (SO) coupling and rotation on trapped spinor Bose-Einstein condensates (BECs). Nature of single particle states is thoroughly examined in the Landau level basis and is shown to support the formation of half-quantum vortex. In the presence of weak s-wave interactions,...
1107.4845v2
2011-08-02
On the Energy Transfer Performance of Mechanical Nanoresonators Coupled with Electromagnetic Fields
We study the energy transfer performance in electrically and magnetically coupled mechanical nanoresonators. Using the resonant scattering theory, we show that magnetically coupled resonators can achieve the same energy transfer performance as for their electrically coupled counterparts, or even outperform them within ...
1108.0633v3
2011-08-13
First Principle Study of Magnetism and Magneto-structural Coupling in Gallium Ferrite
We report a first-principles study of the magnetic properties, site disorder and magneto-structural coupling in multiferroic gallium ferrite (GFO) using local spin density approximation (LSDA+U) of density functional theory. The calculations of the ground state A-type antiferromagnetic structure predict magnetic moment...
1108.2773v1
2011-08-22
Relaxing the Higgs mass bound in singlet extensions of the MSSM
We show that the upper bound on the lightest Higgs mass in the MSSM is relaxed by introducing a singlet which couples to the Higgs fields, even at a large tan beta region, preferable for explaining the muon anomalous magnetic moment. In the models of a singlet extension, it is known that the upper bound is relaxed by a...
1108.4338v2
2011-08-25
Exact dark state solutions of the coupled atomic-molecular Bose-Einstein condensates in an external potential
We consider a coupled nonlinear Schr\"{o}dinger equations describing an atomic Bose-Einstein condensates coupled to a molecular condensates through the stimulated Raman adiabatic passage loaded in an external potential. The existence of dark state are investigated within the full parameter space accounts for all the no...
1108.5000v1
2011-08-25
Quantum Langevin equation of a charged oscillator in a magnetic field and coupled to a heat bath through momentum variables
We obtain the quantum Langevin equation (QLE) of a charged quantum particle moving in a harmonic potential in the presence of a uniform external magnetic field and linearly coupled to a quantum heat bath through momentum variables. The bath is modeled as a collection of independent quantum harmonic oscillators. The QLE...
1108.5142v2
2011-08-26
Plasmon and coupled plasmon-phonon modes in graphene in the presence of inter-band excitation channels
Plasmon and coupled plasmon-phonon modes in graphene are investigated the-oretically within the diagrammatic self-consistent field theory. It shows that two plasmon modes and four coupled plasmon-phonon modes can be excited via intra-and inter-band transition channels. It is found that with increasing q and carrier den...
1108.5265v1
2011-09-12
A general coupled nonlinear oscillator model for event-related (de)synchronization
Changes in the level of synchronization and desynchronization in coupled oscillator systems due to an external stimulus is called event related synchronization or desynchronization (ERS/ERD). Such changes occur in real life systems where the collective activity of the entities of a coupled system is affected by some ex...
1109.2422v1
2011-09-12
Inherent Mach-Zehnder interference with "which-way" detection for single particle scattering in one dimension
We study the coherent transport of single photon in a one-dimensional coupled-resonator-array, "non-locally" coupled to a two-level system. Since its inherent structure is a Mach-Zehnder interferometer, we explain the destructive interference phenomenon of the transmission spectrums according to the effect of which-way...
1109.2470v1
2011-09-13
Stability of Schwarzschild black hole in f(R) gravity with the dynamical Chern-Simons term
We perform the stability analysis of the Schwarzschild black hole in $f(R)$ gravity with the parity-violating Chern-Simons (CS) term coupled to a dynamical scalar field $\theta$. For this purpose, we transform the $f(R)$ gravity into the scalar-tensor theory by introducing a scalaron $\phi$, providing the dynamical Che...
1109.2719v2
2011-09-13
Evidence for Interlayer Electronic Coupling in Multilayer Epitaxial Graphene from Polarization Dependent Coherently Controlled Photocurrent Generation
Most experimental studies to date of multilayer epitaxial graphene on C-face SiC have indicated that the electronic states of different layers are decoupled as a consequence of rotational stacking. We have measured the third order nonlinear tensor in epitaxial graphene as a novel approach to probe interlayer electronic...
1109.2850v1
2011-09-28
Experimental observation of extreme multistability in an electronic system of two coupled Rössler oscillators
We report the first experimental observation of extreme multistability in a controlled laboratory investigation. Extreme multistability arises when infinitely many attractors coexist for the same set of system parameters. The behavior was predicted earlier on theoretical grounds, supported by numerical studies of model...
1109.6267v2
2011-09-28
Interplay between electron-phonon couplings and disorder strength on the transport properties of organic semiconductors
The combined effect of bulk and interface electron-phonon couplings on the transport properties is investigated in a model for organic semiconductors gated with polarizable dielectrics. While the bulk electron-phonon interaction affects the behavior of mobility in the coherent regime below room temperature, the interfa...
1109.6342v1
2011-10-06
Long-distance spin-spin coupling via floating gates
The electron spin is a natural two level system that allows a qubit to be encoded. When localized in a gate defined quantum dot, the electron spin provides a promising platform for a future functional quantum computer. The essential ingredient of any quantum computer is entanglement---between electron spin qubits---com...
1110.1342v1
2011-10-17
Acoustic phonons mediated non-equilibrium spin current in the presence of Rashba and Dresselhaus spin-orbit couplings
The influence of the electrons interaction with longitudinal acoustic phonons on magnetoeletric and spin-related transport effects are investigated. The physical system under consideration has been assumed to be a two dimensional electron gas system with both Rashba and Dreesselhaus spin-orbit couplings. In the works w...
1110.3667v3
2011-10-18
Creation of Matter in the Universe and Groups of Type E7
We relate the mechanism of matter creation in the universe after inflation to a simple and universal mathematical property of extended N > 1 supergravities and related compactifications of superstring theory. We show that in all such models, the inflaton field may decay into vector fields due to a nonminimal scalar-vec...
1110.4048v2
2011-10-20
Holographic non-relativistic fermionic fixed point and bulk dipole coupling
Inspired by the recently discovered non-relativistic fermionic fixed points, we investigate how the presence of bulk dipole coupling modifies the spectral function at one of these novel fixed points. As a result, although the infinite flat band is always visible in the presence of the bulk dipole coupling as well as ch...
1110.4559v3
2011-10-21
Spin-orbit-induced strong coupling of a single spin to a nanomechanical resonator
We theoretically investigate the deflection-induced coupling of an electron spin to vibrational motion due to spin-orbit coupling in suspended carbon nanotube quantum dots. Our estimates indicate that, with current capabilities, a quantum dot with an odd number of electrons can serve as a realization of the Jaynes-Cumm...
1110.4893v2
2011-10-25
An Argument for Nonminimal Higgs Coupling to Gravity
The coupling of gravity to a scalar field raises a number of interesting questions of principle since the usual minimal coupling obtained by replacing ordinary derivatives with covariant derivatives is not available -- they are the same operation on scalar fields. Conformal couplings in the Lagrangian proportional to $...
1110.5549v1
2011-10-25
Light Custodians and Higgs Physics in Composite Models
Composite Higgs models involving partial compositeness of Standard Model fermions typically require the introduction of fermionic partners which are relatively light in realistic scenarios. In this paper, we analyze the role of these light custodian fermions in the phenomenology of the composite Higgs models and show t...
1110.5646v2
2011-12-01
Axial Anomaly, Mismatched Fermi Surfaces and Vector Interaction in Dense Neutral Quark Matter
We report on effects of the q-$\bar{\rm q}$ vector interaction and/or the U(1)$_A$-anomaly-induced chiral-diquark coupling on the charge-neutral quark matter in $\beta$-equilibrium. We show that when the vector coupling is absent, there can appear a cross-over region sandwiched by two critical points in the intermediat...
1112.0075v2
2011-12-06
Radiative coupling and weak lasing of exciton-polariton condensates
In spite of having finite life-time exciton-polaritons in microcavities are known to condense at strong enough pumping of the reservoir. We present an analytical theory of such Bose-condensates on a set of localized one-particle states: condensation centers. To understand physics of these arrays one has to supplement t...
1112.1399v2
2011-12-12
Solving non-Markovian open quantum systems with multi-channel reservoir coupling
We extend the non-Markovian quantum state diffusion (QSD) equation to open quantum systems which exhibit multi-channel coupling to a harmonic oscillator reservoir. Open quantum systems which have multi-channel reservoir coupling are those in which canonical transformation of reservoir modes cannot reduce the number of ...
1112.2716v1
2011-12-13
Critical temperature of a Rashba spin-orbit coupled Bose gas in harmonic traps
We investigate theoretically Bose-Einstein condensation of an ideal, trapped Bose gas in the presence of Rashba spin-orbit coupling. Analytic results for the critical temperature and condensate fraction are derived, based on a semi-classical approximation to the single-particle energy spectrum and density of states, an...
1112.2799v2
2011-12-14
Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
We show that inversion symmetry breaking together with spin-orbit coupling leads to coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides, making possible controls of spin and valley in these 2D materials. The spin-valley coupling at the valence band edges suppresses spin and valley r...
1112.3144v3
2011-12-19
Exploiting boundary states of imperfect spin chains for high-fidelity state transfer
We study transfer of a quantum state through XX spin chains with static imperfections. We combine the two standard approaches for state transfer based on (i) modulated couplings between neighboring spins throughout the spin chain and (ii) weak coupling of the outermost spins to an unmodulated spin chain. The combined a...
1112.4503v2
2011-12-23
Observation of scalar nuclear spin-spin coupling in van der Waals molecules
Scalar couplings between covalently bound nuclear spins are a ubiquitous feature in nuclear magnetic resonance (NMR) experiments, imparting valuable information to NMR spectra regarding molecular structure and conformation. Such couplings arise due to a second-order hyperfine interaction, and, in principle, the same me...
1112.5644v1
2012-02-09
Spin-orbit coupling induced fractionalized Skyrmion excitations in rotating and rapidly quenched spin-1 Bose-Einstein condensates
We investigate the fractionalized Skyrmion excitations induced by spin-orbit coupling in rotating and rapidly quenched spin-1 Bose-Einstein condensates. Our results show that the fractionalized Skyrmion excitation depends on the combination of spin-orbit coupling and rotation, and it originates from a dipole structure ...
1202.1911v3
2012-02-14
Noise Correlations and Coherent Coupling in Solid-State Qubits
This thesis is devoted to the study of quantum mechanical effects that arise in systems of reduced dimensionality. Specifically, we investigate coherence and correlation effects in quantum transport models. In the first part, we present a theory of Markovian and non- Markovian current correlations in nanoscopic conduct...
1202.3161v1
2012-02-17
Competition of different coupling schemes in atomic nuclei
Shell model calculations reveal that the ground and low-lying yrast states of the $N=Z$ nuclei $^{92}_{46}$Pd and $^{96}$Cd are mainly built upon isoscalar spin-aligned neutron-proton pairs each carrying the maximum angular momentum J=9 allowed by the shell $0g_{9/2}$ which is dominant in this nuclear region. This mode...
1202.3918v1
2012-02-22
Lossy Source Coding via Spatially Coupled LDGM Ensembles
We study a new encoding scheme for lossy source compression based on spatially coupled low-density generator-matrix codes. We develop a belief-propagation guided-decimation algorithm, and show that this algorithm allows to approach the optimal distortion of spatially coupled ensembles. Moreover, using the survey propag...
1202.4959v1
2012-02-23
Photon-assisted entanglement creation by minimum-error generalized quantum measurements in the strong coupling regime
We explore possibilities of entangling two distant material qubits with the help of an optical radiation field in the regime of strong quantum electrodynamical coupling with almost resonant interaction. For this purpose the optimum generalized field measurements are determined which are capable of preparing a two-qubit...
1202.5192v2
2012-02-29
Coherence transition in degenerate diffusion equations with mean field coupling
We introduce non-linear diffusion in a classical diffusion advection model with non local aggregative coupling on the circle, that exhibits a transition from an uncoherent state to a coherent one when the coupling strength is increased. We show first that all solutions of the equation converge to the set of equilibria,...
1202.6521v1
2012-03-01
Pionic couplings to the lowest heavy-light mesons of positive and negative parity
We present the method and compute the strong couplings of the lowest and first orbitally excited heavy-light mesons to a soft pion in the static heavy quark limit on the lattice. Besides the usual g^ and \~g couplings, we were able to make the first computation of the coupling h using the relevant radial distributions....
1203.0167v1
2012-03-02
Magnetic Interaction between Surface Engineered Rare-earth Atomic Spins
We report the ab initio study of rare-earth adatoms (Gd) on an insulating surface. This surface is of interest because of previous studies by scanning tunneling microscopy showing spin excitations of transition metal adatoms. The present work is the first study of rare-earth spin-coupled adatoms, as well as the geometr...
1203.0418v1
2012-03-08
Nonequilibrium phases in hybrid arrays with flux qubits and NV centers
We propose a startling hybrid quantum architecture for simulating a localization-delocalization transition. The concept is based on an array of superconducting flux qubits which are coupled to a diamond crystal containing nitrogen-vacancy (NV) centers. The underlying description is a Jaynes-Cummings-lattice in the stro...
1203.1857v2
2012-03-22
Cluster and group synchronization in delay-coupled networks
We investigate the stability of synchronized states in delay-coupled networks where synchronization takes place in groups of different local dynamics or in cluster states in networks with identical local dynamics. Using a master stability approach, we find that the master stability function shows a discrete rotational ...
1203.4916v2
2012-03-22
Constraints on the Universal Varying Yukawa Couplings: from SM-like to Fermiophobic
Varying the Standard Model (SM) fermion Yukawa couplings universally by a generic positive scale factor ($F_{Yu}$), we study the phenomenological fit to the current available experimental results for the Higgs boson search at hadron colliders. We point out that the Higgs production cross section and its decay branching...
1203.5083v3
2012-03-28
Nonperturbative master equation solution of central spin dephasing dynamics
We solve the long-standing central spin problem for a general set of inhomogeneous bath couplings and a large class of initial bath states. We compute the time evolution of the coherence of a central spin coupled to a spin bath by resumming all orders of the time-convolutionless master equation, thus avoiding the need ...
1203.6355v2
2012-06-05
Photon Blockade in the Ultrastrong Coupling Regime
We explore photon coincidence counting statistics in the ultrastrong-coupling regime where the atom-cavity coupling rate becomes comparable to the cavity resonance frequency. In this regime usual normal order correlation functions fail to describe the output photon statistics. By expressing the electric-field operator ...
1206.0944v2
2012-06-08
Probing Color Octet Couplings at the Large Hadron Collider
Color-octet resonances arise in many well motivated theories beyond the standard model. As colored objects they are produced copiously at the LHC and can be discovered in early searches for new physics in dijet final states. Once they are discovered it will be important to measure the couplings of the new resonances to...
1206.1661v2
2012-06-08
Shining Light on Modifications of Gravity
Many modifications of gravity introduce new scalar degrees of freedom, and in such theories matter fields typically couple to an effective metric that depends on both the true metric of spacetime and on the scalar field and its derivatives. Scalar field contributions to the effective metric can be classified as conform...
1206.1809v2
2012-06-14
Controllable exchange coupling between two singlet-triplet qubits
We study controllable exchange coupling between two singlet-triplet qubits. We start from the original second quantized Hamiltonian of a quadruple quantum dot system and obtain the effective spin-spin interaction between the two qubits using the projection operator method. Under a strong uniform external magnetic field...
1206.3112v4
2012-06-13
Phantom Divide Crossing with General Non-minimal Kinetic Coupling
We propose a model of dark energy consists of a single scalar field with a general non-minimal kinetic couplings to itself and to the curvature. We study the cosmological dynamics of the equation of state in this setup. The coupling terms have the form $\xi_{1} R f(\phi)\partial_{\mu}\phi\partial^{\mu}\phi$ and $\xi_{2...
1206.3299v1
2012-06-25
Strong coupling between mechanical modes in a nanotube resonator
We report on the nonlinear coupling between the mechanical modes of a nanotube resonator. The coupling is revealed in a pump-probe experiment where a mode driven by a pump force is shown to modify the motion of a second mode measured with a probe force. In a second series of experiments, we actuate the resonator with o...
1206.5610v1
2012-07-06
Global Analysis of the Higgs Candidate with Mass ~ 125 GeV
We analyze the properties of the Higgs candidate with mass ~ 125 GeV discovered by the CMS and ATLAS Collaborations, constraining the possible deviations of its couplings from those of a Standard Model Higgs boson. The CMS, ATLAS and Tevatron data are compatible with Standard Model couplings to massive gauge bosons and...
1207.1693v2
2012-07-20
Slot-mode-coupled optomechanical crystals
We present a design methodology and analysis of a cavity optomechanical system in which a localized GHz frequency mechanical mode of a nanobeam resonator is evanescently coupled to a high quality factor (Q>10^6) optical mode of a separate nanobeam optical cavity. Using separate nanobeams provides flexibility, enabling ...
1207.5020v1
2012-07-26
Thermodynamics and phase diagram of anisotropic Chern-Simons deformed gauge theories
We consider 3+1-dimensional gauge theories at finite temperature and a finite density of charges which couple to a 2+1-dimensional Chern-Simons operator, giving rise to a theta-term with constant spatial gradient of theta. The strong-coupling limit of thermal N=4 super-Yang-Mills theory with this kind of anisotropic de...
1207.6283v2
2012-07-27
Nonequilibrium Multi-Band Spin Quantum Transport Equations: Spin, Pseudo-Spin, and Total Charge Coupling
Using the superfield nonequilibrium Greens function technique, we derive the spatio-temporal spin magnetization quantum transport equations (SMQTEs) for a two-band model of semiconductors. The relevant variables are the real (Pauli-Dirac) spin, pseudo-spin, and the total charge. The results show that the multi-band rea...
1207.6647v1
2012-07-31
Mass anomalous dimension from Dirac eigenmode scaling in conformal and confining systems
The mode number of the Dirac operator scales with an exponent related to the mass anomalous dimension gamma_m. This relation holds both in IR-conformal systems, as well as in confining systems for large enough eigenvalues. We investigate the Nf=4, 8 and 12 flavor SU(3) systems at several couplings near the chiral limit...
1207.7162v1
2012-08-03
Optical nonlinearity for few-photon pulses on a quantum dot-pillar cavity device
Giant optical nonlinearity is observed under both continuous-wave and pulsed excitation in a deterministically-coupled quantum dot-micropillar system, in a pronounced strong-coupling regime. Using absolute reflectivity measurements we determine the critical intracavity photon number as well as the input and output coup...
1208.0850v1
2012-08-05
The Yang-Mills gradient flow in finite volume
The Yang-Mills gradient flow is considered on the four dimensional torus T^4 for SU(N) gauge theory coupled to N_f flavors of massless fermions in arbitrary representations. The small volume dynamics is dominated by the constant gauge fields. The expectation value of the field strength tensor squared is calculated for ...
1208.1051v2
2012-08-08
Accretion of non-minimally coupled generalized Chaplygin gas into black holes
The mass evolution of Schwarzschild black holes by the absorption of scalar fields is investigated in the scenario of the generalized Chaplygin gas (GCG). The GCG works as a unification picture of dark matter plus dark energy that naturally accelerates the expansion of the Universe. Through elements of the quasi-statio...
1208.1572v1
2012-08-15
Electrical modulation of the edge channel transport in topological insulators coupled to ferromagnetic leads
The counterpropagating edge states of a two-dimensional topological insulator (TI) carry electrons of opposite spins. We investigate the transport properties of edge states in a two-dimensional TI which is contacted to ferromagnetic leads. The application of a side-gate voltage induces a constriction or quantum point c...
1208.3031v1
2012-08-20
A Simple Proof of Threshold Saturation for Coupled Vector Recursions
Convolutional low-density parity-check (LDPC) codes (or spatially-coupled codes) have now been shown to achieve capacity on binary-input memoryless symmetric channels. The principle behind this surprising result is the threshold-saturation phenomenon, which is defined by the belief-propagation threshold of the spatiall...
1208.4080v3
2012-08-23
Coupling of fermionic fields with mass dimensions one to the O'Raifeartaigh model
The objective of this article is to discuss the coupling of fermionic fields with mass dimension one to the O'Raifeartaigh model to study supersymmetry breaking for fermionic fields with mass dimension one. We find that the coupled model has two distinct solutions. The first solution represents a local minimum of the...
1208.4674v1
2012-08-26
Dissipation and detection of polaritons in ultrastrong coupling regime
We have investigated theoretically a dissipative polariton system in the ultrastrong light-matter coupling regime without using the rotating-wave approximation on system-reservoir coupling. Photons in a cavity and excitations in matter respectively couple two large ensembles of harmonic oscillators (photonic and excito...
1208.5181v1
2012-08-29
Optically mediated nonlinear quantum optomechanics
We consider theoretically the optomechanical interaction of several mechanical modes with a single quantized cavity field mode for linear and quadratic coupling. We focus specifically on situations where the optical dissipation is the dominant source of damping, in which case the optical field can be adiabatically elim...
1208.5821v1