By using the normal ordering method, we study the state evolution of an optically driven excitons in a quantum well immersed in a leaky cavity, which was introduced by Yu-Xi Liu et al. [Phys. Rev. A 63 (2001) 033816]....By using the normal ordering method, we study the state evolution of an optically driven excitons in a quantum well immersed in a leaky cavity, which was introduced by Yu-Xi Liu et al. [Phys. Rev. A 63 (2001) 033816]. The influence of the external laser field on the quantum decoherence of a mesoscopically superposed state of the excitons is investigated. Our result shows that, the classical field can compensate the energy dissipation of the excitons. Although the decoherence rate of the excitonic Schr?dinger cat state does not depend on the external field, the phase of the decoherence factor can be well controlled by adjusting the amplitude of the external field as well as the detuning between the field and the transition frequency of the atom.展开更多
When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantu...When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantum data bus for nonlinear nanomechanical resonator, the nonlinearity destroys the dynamical quantum information-storage and maintains the revival of quantum coherence of charge qubit. With the calculation of decoherence factor, we demon- strate the influence of the nonlinearity of nanomechanical resonator on engineered decoherence of charge qubit.展开更多
Known as an engineered reservoir due to fluctuations in trap parameter,a classical source of quantum decoherence is considered for a single trapped ion theoretically.For simplicity it is assumed that the fluctuations ...Known as an engineered reservoir due to fluctuations in trap parameter,a classical source of quantum decoherence is considered for a single trapped ion theoretically.For simplicity it is assumed that the fluctuations involved are white noise processes,which enables us to give a simple master equation description of this source of decoherence.Our results show that the decoherence rate depends on the vibrational quantum number in different ways corresponding to the vibrational excitation sideband used there.Besides,this source of decoherence also leads to occurrence of dissipation in the ion system.展开更多
We revisit the quantum decoherence problem of the center of mass motion of a macroscopic object, which is modelled as a one-dimensional atom chain. Induced by the coupling of the center of mass （C.M） motion with the...We revisit the quantum decoherence problem of the center of mass motion of a macroscopic object, which is modelled as a one-dimensional atom chain. Induced by the coupling of the center of mass （C.M） motion with the inner degrees of freedom, this inner-environment-induced decoherence is reflected by the localization of the C.M wave packet. We show that, the C.M motion is coupled to the inner states only when the chain has interaction with the external potential. This result provides a realistic mechanism for the analysis of the inner-environment-induced localization of a macroscopic object.展开更多
We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of th...We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment,the tunneling element,the initial state of the environment,and the system-environment coupling strength.From the analysis,we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it.展开更多
We investigate the stabilization mechanism of open quantum batteries driven by a classical field in the weak or strong system-reservoir coupling regime.A protocol to improve the steady-state energy storage performance...We investigate the stabilization mechanism of open quantum batteries driven by a classical field in the weak or strong system-reservoir coupling regime.A protocol to improve the steady-state energy storage performance is proposed by engineering the spectral density of a band-gap environment which is described as the superposition of two inhomogeneous Lorentzian spectrums with different weights.We find out that the interplay between the batteryenvironment-bound state and the reservoir memory effect plays a crucial role in the stabilization performance against energy dissipation.The formation of the bound state and the nonMarkovian effect will be strengthened by adjusting the weights of the environment spectral density.In the charging process,the classical field contributes to enhancing the steady ergotropy.Moreover,the manipulation of the spectrum weights results in the speedup scheme of carrying out the energy storage due to the existence of bound states.In the self-discharging process,increasing the spectral weight allows the battery to maintain a higher steady ergotropy.These results provide a practical approach to achieving optimal quantum batteries with better stabilization performance.展开更多
We let a set of beam splitters of vacuum mode with a chosen transmittance parameter η in interaction with a separable coherent states.This model induces the production of an attenuated quantum channels based on entan...We let a set of beam splitters of vacuum mode with a chosen transmittance parameter η in interaction with a separable coherent states.This model induces the production of an attenuated quantum channels based on entangled optical states.Indeed,the decoherence effect is exploited positively here to generate such kind of quantum channels.Next,the amplitude damping and the entanglement amount of these produced channels are enhanced thereafter by a probabilistic quasi amplification process using again a 50 : 50 beam splitter.展开更多
Recently,bidirectional quantum teleportation has attracted a great deal of research attention.However,existing bidirectional teleportation schemes are normally discussed on the basis of perfect quantum environments.In...Recently,bidirectional quantum teleportation has attracted a great deal of research attention.However,existing bidirectional teleportation schemes are normally discussed on the basis of perfect quantum environments.In this paper,we first put forward a bidirectional teleportation scheme to transport three-qubit Greenberger-Horne-Zeilinger（GHZ） states based on controled-not（CNOT） operation and single-qubit measurement.Then,we generalize it to the teleportation of multi-qubit GHZ states.Further,we discuss the influence of quantum noise on our scheme by the example of an amplitude damping channel,then we obtain the fidelity of the teleportation.Finally,we utilize the weak measurement and the corresponding reversing measurement to protect the quantum entanglement,which shows an effective enhancement of the teleportation fidelity.展开更多
Multi-qubit entanglement states are the key resources for various multipartite quantum communication tasks. For a class of generalized three-qubit quantum entanglement, W-like state, we demonstrate that the weak measu...Multi-qubit entanglement states are the key resources for various multipartite quantum communication tasks. For a class of generalized three-qubit quantum entanglement, W-like state, we demonstrate that the weak measurement and the reversal measurement are capable of suppressing the amplitude damping decoherence by reducing the initial damping factor into a smaller equivalent damping factor. Furthermore, we propose an iteration method in the weak measurement and the reversal measurement to enhance the success probability of the total measurements. Finally, we discuss how the number of the iterations influences the overall effect of decoherence suppression, and find that the ＂half iteration＂ method is a better option that has more practical value.展开更多
The lower bounds of the evolution time between two distinguishable states of a system, defined as quantum speed limit time, can characterize the maximal speed of quantum computers and communication channels. We study ...The lower bounds of the evolution time between two distinguishable states of a system, defined as quantum speed limit time, can characterize the maximal speed of quantum computers and communication channels. We study the quantum speed limit time between the composite quantum states and their target states in the presence of nondissipative decoherence.For the initial states with maximally mixed marginals, we obtain the exact expressions of the quantum speed limit time which mainly depend on the parameters of the initial states and the decoherence channels. Furthermore, by calculating the quantum speed limit time for the time-dependent states started from a class of initial states, we discover that the quantum speed limit time gradually decreases in time, and the decay rate of the quantum speed limit time would show a sudden change at a certain critical time. Interestingly, at the same critical time, the composite system dynamics would exhibit a sudden transition from classical decoherence to quantum decoherence.展开更多
We investigate the quantum to classical transition induced by two-particle interaction via a system of periodically kicked particles.The classical dynamics of particle 1 is almost unaffected in condition that its mass...We investigate the quantum to classical transition induced by two-particle interaction via a system of periodically kicked particles.The classical dynamics of particle 1 is almost unaffected in condition that its mass is much larger than that of particle 2.Interestingly,such classically weak influence leads to the quantum to classical transition of the dynamical behavior of particle 1.Namely,the quantum diffusion of this particle undergoes the transition from dynamical localization to the classically chaotic diffusion with the decrease of the effective Planck constantħeff.The behind physics is due to the growth of entanglement in the system.The classically very weak interaction leads to the exponential decay of purity in condition that the classical dynamics of external degrees freedom is strongly chaotic.展开更多
It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (...It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (QST)protocol,how the efficacy of QST is reduced by the quantum decoherence induced by a spatially distributed environment.Here,the environment is universally modeled as a bath of fermions located in different positions.By making use of theirreducible tensor method in angular momentum theory,we investigate the effect of environment on the efficiency of QSTfor both cases at zero and finite temperatures.We not only show the generic exponential decay of QST efficiency as thenumber of sites increase,but also find some counterintuitive effect,the QST can be enhanced as temperature increasesin some cases.展开更多
We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screeni...We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr6hlich transformation in the qubit-cavity-resonator system, we calculate the decoherenee factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.展开更多
We investigate the roles of different qubit-environment decoherence models on the entanglement trapping of two qubits. By considering three environmental models （the single photonic band gap model, the common photoni...We investigate the roles of different qubit-environment decoherence models on the entanglement trapping of two qubits. By considering three environmental models （the single photonic band gap model, the common photonic band gap model, and the two independent photonic band gaps model）, we note that the final values of entanglement trapping are determined by these different models. We also give the conditions of obtaining the larger entanglement trapping by comparing two-qubit entanglement dynamics in different decoherence models. Moreover, the comparison of entanglement trapping between two Bell-like states in the same decoherence model are also carried out.展开更多
The conformational change of biological macromolecule is investigated from the point of quantum transition.A quantum theory on protein folding is proposed.Compared with other dynamical variables such as mobile electro...The conformational change of biological macromolecule is investigated from the point of quantum transition.A quantum theory on protein folding is proposed.Compared with other dynamical variables such as mobile electrons,chemical bonds and stretching-bending vibrations the molecular torsion has the lowest energy and can be looked as the slow variable of the system.Simultaneously,from the multi-minima property of torsion potential the local conformational states are well defined.Following the idea that the slow variables slave the fast ones and using the nonadiabaticity operator method we deduce the Hamiltonian describing conformational change.It is shown that the influence of fast variables on the macromolecule can fully be taken into account through a phase transformation of slow variable wave function.Starting from the conformation-transition Hamiltonian the nonradiative matrix element was calculated and a general formulas for protein folding rate was deduced.The analytical form of the formula was utilized to study the temperature dependence of protein folding rate and the curious non-Arrhenius temperature relation was interpreted.By using temperature dependence data the multi-torsion correlation was studied.The decoherence time of quantum torsion state is estimated.The proposed folding rate formula gives a unifying approach for the study of a large class problems of biological conformational change.展开更多
The entanglement dynamics of a two-qutrit system under decoherence from a spin environment is investigated by using negativityas entanglement measure. Our results imply that the entanglement evolution depends not only...The entanglement dynamics of a two-qutrit system under decoherence from a spin environment is investigated by using negativityas entanglement measure. Our results imply that the entanglement evolution depends not only on the coupling strength and thetunneling elements of the environment but also on the number of the freedom degrees and the initial state of the environment.展开更多
We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking fi...We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence spontaneously.This spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary conditions.In particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to infinity.Our investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.展开更多
文摘By using the normal ordering method, we study the state evolution of an optically driven excitons in a quantum well immersed in a leaky cavity, which was introduced by Yu-Xi Liu et al. [Phys. Rev. A 63 (2001) 033816]. The influence of the external laser field on the quantum decoherence of a mesoscopically superposed state of the excitons is investigated. Our result shows that, the classical field can compensate the energy dissipation of the excitons. Although the decoherence rate of the excitonic Schr?dinger cat state does not depend on the external field, the phase of the decoherence factor can be well controlled by adjusting the amplitude of the external field as well as the detuning between the field and the transition frequency of the atom.
文摘When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantum data bus for nonlinear nanomechanical resonator, the nonlinearity destroys the dynamical quantum information-storage and maintains the revival of quantum coherence of charge qubit. With the calculation of decoherence factor, we demon- strate the influence of the nonlinearity of nanomechanical resonator on engineered decoherence of charge qubit.
基金Chinese Postdoctoral Fund and National Natural Science Foundation of China
文摘Known as an engineered reservoir due to fluctuations in trap parameter,a classical source of quantum decoherence is considered for a single trapped ion theoretically.For simplicity it is assumed that the fluctuations involved are white noise processes,which enables us to give a simple master equation description of this source of decoherence.Our results show that the decoherence rate depends on the vibrational quantum number in different ways corresponding to the vibrational excitation sideband used there.Besides,this source of decoherence also leads to occurrence of dissipation in the ion system.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10547106, 90203018, 10474104, and 60433050, and the National Fundamental Research Program of China under Grant Nos. 2001CB309310 and 2005CB724508 L. Zheng thanks sincerely C.P. Sun and P. Zhang for their helpful discussions.
文摘We revisit the quantum decoherence problem of the center of mass motion of a macroscopic object, which is modelled as a one-dimensional atom chain. Induced by the coupling of the center of mass （C.M） motion with the inner degrees of freedom, this inner-environment-induced decoherence is reflected by the localization of the C.M wave packet. We show that, the C.M motion is coupled to the inner states only when the chain has interaction with the external potential. This result provides a realistic mechanism for the analysis of the inner-environment-induced localization of a macroscopic object.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11105001,11004001,and 10975125
文摘We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment,the tunneling element,the initial state of the environment,and the system-environment coupling strength.From the analysis,we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it.
基金supported by Postgraduate Research and Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_3424)funded by SCOAP^(3)。
文摘We investigate the stabilization mechanism of open quantum batteries driven by a classical field in the weak or strong system-reservoir coupling regime.A protocol to improve the steady-state energy storage performance is proposed by engineering the spectral density of a band-gap environment which is described as the superposition of two inhomogeneous Lorentzian spectrums with different weights.We find out that the interplay between the batteryenvironment-bound state and the reservoir memory effect plays a crucial role in the stabilization performance against energy dissipation.The formation of the bound state and the nonMarkovian effect will be strengthened by adjusting the weights of the environment spectral density.In the charging process,the classical field contributes to enhancing the steady ergotropy.Moreover,the manipulation of the spectrum weights results in the speedup scheme of carrying out the energy storage due to the existence of bound states.In the self-discharging process,increasing the spectral weight allows the battery to maintain a higher steady ergotropy.These results provide a practical approach to achieving optimal quantum batteries with better stabilization performance.
文摘We let a set of beam splitters of vacuum mode with a chosen transmittance parameter η in interaction with a separable coherent states.This model induces the production of an attenuated quantum channels based on entangled optical states.Indeed,the decoherence effect is exploited positively here to generate such kind of quantum channels.Next,the amplitude damping and the entanglement amount of these produced channels are enhanced thereafter by a probabilistic quasi amplification process using again a 50 : 50 beam splitter.
基金Project supported by the National Natural Science Foundation of China(Grant No.61172071)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.16JK1711)+1 种基金the International Scientific Cooperation Program of Shaanxi Province,China(Grant No.2015KW-013)the Natural Science Foundation Research Project of Shaanxi Province,China(Grant No.2016JQ6033)
文摘Recently,bidirectional quantum teleportation has attracted a great deal of research attention.However,existing bidirectional teleportation schemes are normally discussed on the basis of perfect quantum environments.In this paper,we first put forward a bidirectional teleportation scheme to transport three-qubit Greenberger-Horne-Zeilinger（GHZ） states based on controled-not（CNOT） operation and single-qubit measurement.Then,we generalize it to the teleportation of multi-qubit GHZ states.Further,we discuss the influence of quantum noise on our scheme by the example of an amplitude damping channel,then we obtain the fidelity of the teleportation.Finally,we utilize the weak measurement and the corresponding reversing measurement to protect the quantum entanglement,which shows an effective enhancement of the teleportation fidelity.
基金supported by the National Natural Science Foundation of China(Grant No.61172071)the International Scientific Cooperation Program of Shaanxi Province,China(Grant No.2015KW-013)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.16JK1711)
文摘Multi-qubit entanglement states are the key resources for various multipartite quantum communication tasks. For a class of generalized three-qubit quantum entanglement, W-like state, we demonstrate that the weak measurement and the reversal measurement are capable of suppressing the amplitude damping decoherence by reducing the initial damping factor into a smaller equivalent damping factor. Furthermore, we propose an iteration method in the weak measurement and the reversal measurement to enhance the success probability of the total measurements. Finally, we discuss how the number of the iterations influences the overall effect of decoherence suppression, and find that the ＂half iteration＂ method is a better option that has more practical value.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61178012 and 11304179)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant Nos.20123705120002 and 20133705110001)+1 种基金the Natural Science Foundation of Shandong Province of China(Grant No.ZR2014AP009)the Scientific Research Foundation of Qufu Normal University
文摘The lower bounds of the evolution time between two distinguishable states of a system, defined as quantum speed limit time, can characterize the maximal speed of quantum computers and communication channels. We study the quantum speed limit time between the composite quantum states and their target states in the presence of nondissipative decoherence.For the initial states with maximally mixed marginals, we obtain the exact expressions of the quantum speed limit time which mainly depend on the parameters of the initial states and the decoherence channels. Furthermore, by calculating the quantum speed limit time for the time-dependent states started from a class of initial states, we discover that the quantum speed limit time gradually decreases in time, and the decay rate of the quantum speed limit time would show a sudden change at a certain critical time. Interestingly, at the same critical time, the composite system dynamics would exhibit a sudden transition from classical decoherence to quantum decoherence.
基金the National Natural Science Foundation of China(Grant Nos.11864014 and 11804130).
文摘We investigate the quantum to classical transition induced by two-particle interaction via a system of periodically kicked particles.The classical dynamics of particle 1 is almost unaffected in condition that its mass is much larger than that of particle 2.Interestingly,such classically weak influence leads to the quantum to classical transition of the dynamical behavior of particle 1.Namely,the quantum diffusion of this particle undergoes the transition from dynamical localization to the classically chaotic diffusion with the decrease of the effective Planck constantħeff.The behind physics is due to the growth of entanglement in the system.The classically very weak interaction leads to the exponential decay of purity in condition that the classical dynamics of external degrees freedom is strongly chaotic.
基金Supported by the NSFC under Grant Nos.10775048,10704023NFRPC under Grant No.2007CB925204+1 种基金New Century Excellent Talents in University under Grant No.NCET-08-0682the Scientific Research Fund of Hunan Provincial Education Department of China under Grant No.07C579
文摘It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (QST)protocol,how the efficacy of QST is reduced by the quantum decoherence induced by a spatially distributed environment.Here,the environment is universally modeled as a bath of fermions located in different positions.By making use of theirreducible tensor method in angular momentum theory,we investigate the effect of environment on the efficiency of QSTfor both cases at zero and finite temperatures.We not only show the generic exponential decay of QST efficiency as thenumber of sites increase,but also find some counterintuitive effect,the QST can be enhanced as temperature increasesin some cases.
基金Supported by National Natural Science Foundation of China under Grant Nos. 0547101 and 10604002
文摘We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr6hlich transformation in the qubit-cavity-resonator system, we calculate the decoherenee factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61178012 and 11247240)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123705120002)+3 种基金the Open Project of State Key Laboratory of Crystal Material in Shandong University, China (Grant No. KF1103)the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ024)the Youth Funds from Qufu Normal University, China (Grant No. XJ201219)the Scientific Research Foundation for Doctors of Qufu Normal University, China (Grant No. BSQD20110132)
文摘We investigate the roles of different qubit-environment decoherence models on the entanglement trapping of two qubits. By considering three environmental models （the single photonic band gap model, the common photonic band gap model, and the two independent photonic band gaps model）, we note that the final values of entanglement trapping are determined by these different models. We also give the conditions of obtaining the larger entanglement trapping by comparing two-qubit entanglement dynamics in different decoherence models. Moreover, the comparison of entanglement trapping between two Bell-like states in the same decoherence model are also carried out.
文摘The conformational change of biological macromolecule is investigated from the point of quantum transition.A quantum theory on protein folding is proposed.Compared with other dynamical variables such as mobile electrons,chemical bonds and stretching-bending vibrations the molecular torsion has the lowest energy and can be looked as the slow variable of the system.Simultaneously,from the multi-minima property of torsion potential the local conformational states are well defined.Following the idea that the slow variables slave the fast ones and using the nonadiabaticity operator method we deduce the Hamiltonian describing conformational change.It is shown that the influence of fast variables on the macromolecule can fully be taken into account through a phase transformation of slow variable wave function.Starting from the conformation-transition Hamiltonian the nonradiative matrix element was calculated and a general formulas for protein folding rate was deduced.The analytical form of the formula was utilized to study the temperature dependence of protein folding rate and the curious non-Arrhenius temperature relation was interpreted.By using temperature dependence data the multi-torsion correlation was studied.The decoherence time of quantum torsion state is estimated.The proposed folding rate formula gives a unifying approach for the study of a large class problems of biological conformational change.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10947115, 10975125 and 11004001)
文摘The entanglement dynamics of a two-qutrit system under decoherence from a spin environment is investigated by using negativityas entanglement measure. Our results imply that the entanglement evolution depends not only on the coupling strength and thetunneling elements of the environment but also on the number of the freedom degrees and the initial state of the environment.
基金supported by the National Natural Science Foundation of China(Grant Nos.11504241,and 11374032)the National Key Basic Research Program(Grant No.2014CB848700)Natural Science Foundation of Shenzhen University(Grants No.201551)
文摘We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence spontaneously.This spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary conditions.In particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to infinity.Our investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.
