查看更多>>摘要：The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos,recently giving rise to intense debates.The process of thermalization is intricate,involving many time-evolution trajectories in the reduced Hilbert space of the system.By considering two different expansion forms of the density matrices adopted in the biorthogonal and right-state time evolutions,we derive two versions of the Gorini-Kossakowski-Sudarshan-Lindblad(GKSL)master equations describing the non-Hermitian systems coupled to a bosonic heat bath in thermal equilibrium.By solving the equations,we identify a sufficient condition for thermalization under both time evolutions,resulting in Boltzmann biorthogonal and right-eigenstate statistics,respectively.This finding implies that the recently proposed biorthogonal random matrix theory needs an appropriate revision.Moreover,we exemplify the precise dynamics of thermalization and thermodynamic properties with test models.
查看更多>>摘要：We propose a simple quantum voting machine using microwave photon qubit encoding,based on a setup comprising multiple microwave cavities and a coupled superconducting flux qutrit.This approach primarily relies on a multi-control single-target quantum phase gate.The scheme offers operational simplicity,requiring only a single step,while ensuring verifiability through the measurement of a single qubit phase information to obtain the voting results.It provides voter anonymity,as the voting outcome is solely tied to the total number of affirmative votes.Our quantum voting machine also has scalability in terms of the number of voters.Additionally,the physical realization of the quantum voting machine is general and not limited to circuit quantum electrodynamics.Quantum voting machine can be implemented as long as the multi-control single-phase quantum phase gate is realized in other physical systems.Numerical simulations indicate the feasibility of this quantum voting machine within the current quantum technology.
查看更多>>摘要：This work focuses on the evolution behaviors of ring dark solitons(RDSs)and the following vortices after the collapses of RDSs in spin-1 Bose-Einstein condensates.We find that the weighted average of the initial depths of three components determines the number and motion trajectories of vortex dipoles.For the weighted average of the initial depths below the critical depth,two vortex dipoles form and start moving along the horizontal axis.For the weighted average depth above the critical depth,two or four vortex dipoles form,and all start moving along the vertical axis.For the RDS with weighted average depth at exactly the critical point,four vortex dipoles form,half of the vortex dipoles initiate movement vertically,and the other half initiate movement horizontally.Our conclusion is applicable to the two-component system studied in earlier research,indicating its universality.
查看更多>>摘要：Fractional orbital angular momentum(OAM)vortex beams present a promising way to increase the data throughput in optical communication systems.Nevertheless,high-precision recognition of fractional OAM with different propagation distances remains a significant challenge.We develop a convolutional neural network(CNN)method to realize high-resolution recognition of OAM modalities,leveraging asymmetric Bessel beams imbued with fractional OAM.Experimental results prove that our method achieves a recognition accuracy exceeding 94.3％for OAM modes,with an interval of 0.05,and maintains a high recognition accuracy above 92％across varying propagation distances.The findings of our research will be poised to significantly contribute to the deployment of fractional OAM beams within the domain of optical communications.
查看更多>>摘要：Quantum nonreciprocity,such as nonreciprocal photon blockade,has attracted a great deal of attention due to its unique applications in quantum information processing.Its implementation primarily relies on rotating nonlinear systems,based on the Sagnac effect.Here,we propose an all-optical approach to achieve nonreciprocal photon blockade in an on-chip microring resonator coupled to a V-type Rb atom,which arises from the Zeeman splittings of the atomic hyperfine sublevels induced by the fictitious magnetic field of a circularly polarized control laser.The system manifests single-photon blockade or multi-photon tunneling when driven from opposite directions.This nonreciprocity results from the directional detunings between the countercirculating probe fields and the V-type atom,which does not require the mechanical rotation and facilitates integration.Our work opens up a new route to achieve on-chip integrable quantum nonreciprocity,enabling applications in chiral quantum technologies.
查看更多>>摘要：In comparison to bright pulses,better stability that is not susceptible to loss makes dark pulses accessible for applications in such fields as signal processing,optics sensing,and quantum communication.Here we investigate the dual-wavelength domain-wall dark pulse generation in a graded-index multimode fiber(GIMF)based anoma-lous dispersion single-mode fiber(SMF)laser.By optimizing intra-cavity nonlinearity and pulse polarization,the mode-locked states can evolve each other between bright pulses,dark pulses,and bright-dark pulse pairs.The evolution mechanism among them may be relevant to the coherent mode superposition,spectral filtering,and mode selection in SMF-GIMF-SMF hybrid-fiber modulation devices that affect the pulse formation and evolution in temporal,frequency,and space domains.These results provide a valuable reference for promoting further development of nonlinear optics and ultrafast optics,in which ultrafast photonic devices,with low cost,simple manufacture as well as wide adaptability,as novel pulsed generation technique,play a vital role.
查看更多>>摘要：When pursuing femtosecond-scale ultrashort pulse optical communication,one cannot overlook higher-order nonlinear effects.Based on the fundamental theoretical model of the variable coefficient coupled high-order nonlinear Schrödinger equation,we analytically explore the evolution of optical solitons in the presence of high-order nonlinear effects.Moreover,the interactions between two nearby optical solitons and their transmission in a nonuniform fiber are investigated.The stability of optical soliton transmission and interactions are found to be destroyed to varying degrees due to higher-order nonlinear effects.The outcomes may offer some theoretical references for achieving ultra-high energy optical solitons in the future.
查看更多>>摘要：High-order quantum coherence reveals the statistical correlation of quantum particles.Manipulation of quan-tum coherence of light in the temporal domain enables the production of the single-photon source,which has become one of the most important quantum resources.High-order quantum coherence in the spatial domain plays a crucial role in a variety of applications,such as quantum imaging,holography,and microscopy.However,the active control of second-order spatial quantum coherence remains a challenging task.Here we predict theoreti-cally and demonstrate experimentally the first active manipulation of second-order spatial quantum coherence,which exhibits the capability of switching between bunching and anti-bunching,by mapping the entanglement of spatially structured photons.We also show that signal processing based on quantum coherence exhibits robust resistance to intensity disturbance.Our findings not only enhance existing applications but also pave the way for broader utilization of higher-order spatial quantum coherence.
查看更多>>摘要：Detecting tiny deformations or vibrations,particularly those associated with strains below 1％,is essential in various technological applications.Traditional intrinsic materials,including metals and semiconductors,face challenges in simultaneously achieving initial metallic state and strain-induced insulating state,hindering the development of highly sensitive mechanical sensors.Here we report an ultrasensitive mechanical sensor based on a strain-induced tunable ordered array of metallic and insulating states in the single-crystal bronze-phase vanadium dioxide[VO2(B)]quantum material.It is shown that the initial metallic state in the VO2(B)flake can be tuned to the insulating state by applying a weak uniaxial tensile strain.Such a unique property gives rise to a record-high gauge factor of above 607970,surpassing previous values by an order of magnitude,with excellent linearity and mechanical resilience as well as durability.As a proof-of-concept application,we use our proposed mechanical sensor to demonstrate precise sensing of the micro piece,gentle airflows and water droplets.We attribute the superior performance of the sensor to the strain-induced continuous metal-insulator transition in the single-crystal VO2(B)flake,evidenced by experimental and simulation results.Our findings highlight the potential of exploiting correlated quantum materials for next-generation ultrasensitive flexible mechanical sensors,addressing critical limitations in traditional materials.
查看更多>>摘要：Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemen-tal filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb3 band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.The effective degeneracy near the secondary valence band promotes more valleys to participate in electric transport,leading to a carrier mobility of more than the threefold and nearly twofold effective mass for F0.1Co4Sb12 compared to Co4Sb12.This work provides a new and promising route to boost the thermoelectric properties of p-type skutterudites.
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