We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum ...We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided photons.The perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM dynamics.For the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the atom.Our attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian behavior.An asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective single-mode.We also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.展开更多
In quantum open systems,non-Markovianity is an important phenomenon that allows a backflow of information from the environment to the system.In this work,we investigate the non-Markovianity problems in two different t...In quantum open systems,non-Markovianity is an important phenomenon that allows a backflow of information from the environment to the system.In this work,we investigate the non-Markovianity problems in two different types of channels,where the system-environment interactions are treated with and without the rotating-wave approximation(RWA).We employ the quantum interferometric power(QIP)to quantify the non-Markovian dynamics,which is the minimal quantum Fisher information obtained by the local unitary evolution in a bipartite system.By the hierarchy equation method,we calculate the dynamical evolution of the QIP in the non-RWA case.The results show that the dynamical behavior under the non-RWA is significantly different from that under the RWA in both weak and strong coupling.Moreover,in the non-RWA case,we also find the nonmonotonic behavior of the non-Markovianity measure with the variation of coupling strength,which is caused by the competition between the rotating-wave terms and the counterrotating-wave terms.As a result,we highlight the importance of the counterrotating-wave terms for the influence of non-Markovianity.展开更多
We study the non-Markovianity of open qubit systems using the measure N proposed by Breuer, Laine and Piilo [Phys. Rev. Lett. 103 210401 （2009）]. We find that for the three types of quantum noises, amplitude-damping...We study the non-Markovianity of open qubit systems using the measure N proposed by Breuer, Laine and Piilo [Phys. Rev. Lett. 103 210401 （2009）]. We find that for the three types of quantum noises, amplitude-damping, dephasing and depolarizing noises, there exist some non-Markovian time intervals whose distribution is independent of the selection of the pair of initial states. Therefore, the maximization in the definition of measure N can be actually removed without influencing the detection of non-Markovianity.展开更多
The sudden death of entanglement is investigated for the non-Markovian dynamic process of a pair of interacting flux qubits under a thermal bath. The results show that, for initially two-qubit entangled states, entang...The sudden death of entanglement is investigated for the non-Markovian dynamic process of a pair of interacting flux qubits under a thermal bath. The results show that, for initially two-qubit entangled states, entanglement sudden death （ESD） always happens in the thermal reservoir, where its appearance strongly depends on the environment. In particular, ESD of the qubits occurs more easily for the non-Markovian process than for the Markovian one.展开更多
The models of two qubits separately trapped in two independent Markovian or non-Markovian environments have been investigated. The distinction of the two-qubit entanglement dynamics in different environments has also ...The models of two qubits separately trapped in two independent Markovian or non-Markovian environments have been investigated. The distinction of the two-qubit entanglement dynamics in different environments has also been discussed in detail. The results show that, in non-Markovian environments, the possible usage time of entanglement can be extended due to its memory effect. On the other hand, we note that, compared to Markovian environments, the two-qubit entanglement could be protected better in non-Markovian environments by modulating the detuning between qubits and cavities. Finally, an intuitive physicM interpretation for these results is given.展开更多
This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values...This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values of entanglement can be obtained for an initially factorized state of the two-qubit system. The maximal value of the entanglement increases as the detuning grows. Moreover, the entanglement induced by non-Maxkovian environments is more robust against the asymmetrical couplings between the two qubits and the reservoir. Based on this system, we also show that quantum state transfer can be implemented for arbitrary input states with high fidelity in the non-Markovian regime rather than the Markovian case in which only some particular input states can be successfully transferred.展开更多
We investigate the non-Markovian effects on the entanglement transfer to the distant non-interacting atom qubits,which are embedded in a coupled superconducting resonator.The master equation governing the dynamics of ...We investigate the non-Markovian effects on the entanglement transfer to the distant non-interacting atom qubits,which are embedded in a coupled superconducting resonator.The master equation governing the dynamics of the system is derived by the non-Markovian quantum state diffusion(NMQSD)method.Based on the solution,we show that the memory effect of the environment can lead to higher entanglement revival and make the entanglement last for a longer time.That is to say,the non-Markovian environment can enhance the entanglement transfer.It is also found that the maximum entanglement transferred to distant atoms can be modified by appropriately selecting the frequency of the modulated intercavity coupling.Moreover,with the initial anti-correlated state,the entanglement between the cavity fields can be almost completely transferred to the separated atoms.Lastly,we show that the memory effect has a significant impact on the generation of entanglement from the initial non-entangled states.展开更多
The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the incre...The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the increase of squeeze parameter r, due to the augmenting of average photon number of every mode in the squeezed vacuum cavity. Second, there appear entanglement revivals after the complete disentanglement for the ease of even parity initial Bell state, while there occur the entanglement decrease and the entanglement revival before the complete disentanglement for the case of odd parity initial Bell state. The results are quite different from those for the case of qubits in a vacuum cavity.展开更多
We investigate the time evolution of quantum correlations, which are measured by Gaussian quantum discord in a continuous-variable bipartite system subject to common and independent non-Markovian environments. Conside...We investigate the time evolution of quantum correlations, which are measured by Gaussian quantum discord in a continuous-variable bipartite system subject to common and independent non-Markovian environments. Considering an initial two-mode Gaussian symmetric squeezed thermal state, we show that quantum correlations can be created during the non-Markovian evolution, which is different from the Markovian process. Furthermore, we find that the temperature is a key factor during the evolution in non-Markovian environments. For common reservoirs, a maximum creation of quantum correlations may occur under an appropriate temperature. For independent reservoirs, the non-Markovianity of the total system corresponds to the subsystem whose temperature is higher. In both common and independent environments, the Gaussian quantum discord is influenced by the temperature and the photon number of each mode.展开更多
We investigate the sudden birth and sudden death of entanglement of two qubits interacting with uncorrelated structured reservoirs. The system is initially prepared in two-qubit extended Werner-like state. We work out...We investigate the sudden birth and sudden death of entanglement of two qubits interacting with uncorrelated structured reservoirs. The system is initially prepared in two-qubit extended Werner-like state. We work out the dependence of the entanglement dynamics on both non-Markovian environments and the purity of initial state, and show that non-Markovian environments and the purity can control the time of the two-qubit entanglement sudden death and the reservoirs＇ entanglement sudden birth. Furthermore, under the conditions of different purity and initial entangIement, the revival of qubits＇ entanglement can manifest before, simultaneously or even after the disentanglement of their corresponding reservoirs.展开更多
We investigate the non-Markovian behavior in open quantum systems from an information-theoretic perspective. Our main tool is the max-relative entropy, which quantifies the maximum probability with which a state ρ ca...We investigate the non-Markovian behavior in open quantum systems from an information-theoretic perspective. Our main tool is the max-relative entropy, which quantifies the maximum probability with which a state ρ can appear in a convex decomposition of a state σ. This operational interpretation provides a new view for the non-Markovian process.We also find that max-relative entropy can be the witness and measure of non-Markovian processes. As applications, some examples are also given and compared with other measures in this paper.展开更多
Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies.In this context, we study a system S that is...Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies.In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel.We also consider dipole-dipole interactions(DDIs) between the system and ancilla, which are responsible for strong correlations.We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments.We show that DDIs are not only better than detuning at protecting the information(without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics.In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics.In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning.We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information.展开更多
We study the nonlocal non-Markovian effects through local interactions between two subsystems and the correspond- ing two environments. It has been found that the initial correlations between two environments can turn...We study the nonlocal non-Markovian effects through local interactions between two subsystems and the correspond- ing two environments. It has been found that the initial correlations between two environments can turn a Markovian to a non-Markovian regime with extra control on the local interaction time. We further research the nonlocal non-Markovian effects from two situations： without extra control, the nonlocal non-Markovian effects only appear under the condition that two local dynamics are non-Markovian-non-Markovian （both of the two local dynamics are non-Markovian） or Markovian- non-Markovian, but not under the condition of Markovian-Markovian; with extra control, the nonlocal non-Markovian effects can occur under the condition of Markovian-Markovian. It shows that the function of correlations between two environments has an upper bound, which makes a flow of information from the environment back to the global system beginning finitely earlier than that back to one of the two local systems, not infinitely. Then, we proposed two special ways to distribute classical correlations between two environments without initial correlations. Finally, from numerical solutions in the spin star configuration, we found that the self-correlation （internal correlation） of each environment promotes the nonlocal non-Markovian effects.展开更多
The dynamics of two nanospheres nonlinearly coupling with non-Markovian reservoir is investigated. A master equation of the two nanospheres is derived by employing quantum state diffusion method. It is shown that the ...The dynamics of two nanospheres nonlinearly coupling with non-Markovian reservoir is investigated. A master equation of the two nanospheres is derived by employing quantum state diffusion method. It is shown that the nonlinear coupling can improve the non-Markovianity. Due to the sharing of the common non-Markovian environment, the state transfer between the two nanospheres can be realized. The entanglement and the squeezing of the individual mode, as well as the jointed two-mode are analyzed. The present system can be realized by trapping two nanospheres in a wideband cavity, which might provide a method to study adjustable non-Markovian dynamics of mechanical motion.展开更多
The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, ...The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value.展开更多
We study the entanglement （measured by negativity） evolution and the non-Markovianity for the dynamical process of a spin-S system embedded in dephasing environments. The exact analytical solution is presented, whic...We study the entanglement （measured by negativity） evolution and the non-Markovianity for the dynamical process of a spin-S system embedded in dephasing environments. The exact analytical solution is presented, which shows that the decoherence function governs the evolutions of coherence, entanglement, and the non-Markovianity of the correspond- ing dynamical processes. For Ohmic and sub-Ohmic reservoirs, the negativity decreases monotonically in time and the corresponding dynamics is Markovian. While for super-Ohmic reservoirs with non-monotonic decoherence function, the negativity appears as the phenomenon of revival and the corresponding dynamics is non-Markovian. The relation between non-Markovianity and the system dimension is studied.展开更多
Preventing quantum entanglement from decoherence effect is of theoretical and practical importance in the quantum information processing technologies.In this regard,we consider the entanglement dynamics of two identic...Preventing quantum entanglement from decoherence effect is of theoretical and practical importance in the quantum information processing technologies.In this regard,we consider the entanglement dynamics of two identical qubits where the qubits which are coupled to two independent（Markovian and/or non-Markovian） as well as a common reservoir at zero temperature are further interacted with a classical driving laser field.Then,we study the preservation of generated two-qubit entanglement in various situations using the concurrence measure.It is shown that by applying the classical driving field and so the possibility of controlling the Rabi frequency,the amount of entanglement of the two-qubit system is improved in the off-resonance condition between the qubit and the central cavity frequencies（central detuning） in both non-Markovian and Markovian reservoirs.While the central detuning has a constructive role,the detuning between the qubit and the classical field（laser detuning） affects negatively on the entanglement protection.The obtained results show that long-living entanglement in the non-Markovian reservoir is more accessible than in the Markovian reservoir.We demonstrate that,in a common reservoir non-zero stationary entanglement is achievable whenever the two-qubit system is coupled to the reservoir with appropriate values of relative coupling strengths.展开更多
We present a paradigmatic method for exactly studying non-Markovian dynamics of a multi-level V-type atom interacting with a zero-temperature bosonic bath. Special attention is paid to the entanglement evolution and t...We present a paradigmatic method for exactly studying non-Markovian dynamics of a multi-level V-type atom interacting with a zero-temperature bosonic bath. Special attention is paid to the entanglement evolution and the dynamical nonMarkovianity of a three-level V-type atom. We find that the entanglement negativity decays faster and non-Markovianity is smaller in the resonance regions than those in the non-resonance regions. More importantly, the quantum interference between the dynamical non-Markovianities induced by different transition channels is manifested, and the frequency domains for constructive and destructive interferences are found.展开更多
We study the non-Markovianity of the single qubit system coupled with an isotropic Lipkin-Meshkov-Glick（LMG）model by an effective method proposed by Breuer et al.（Breuer H P and Piilo J 2009 Europhys. Lett. 85 5004...We study the non-Markovianity of the single qubit system coupled with an isotropic Lipkin-Meshkov-Glick（LMG）model by an effective method proposed by Breuer et al.（Breuer H P and Piilo J 2009 Europhys. Lett. 85 5004）. It is discovered that the non-Markovianity is concerned with the quantum phase transitions（QPTs）. In the open system, we present that the strong coupling inside the bath and the strong interaction between the system and bath can enhance the degree of non-Markovianity. Moreover, the non-Markovianity is stronger and more sensitive for the bath in the symmetric phase than the symmetry broken phase.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11935006,12075082,12205088,and 11975095)the Science and Technology Innovation Program of Hunan Province,China(Grant No.2020RC4047)+1 种基金the Scientific Research Fund of the Hunan Provincial Education Department(Grant No.21B0639)Hunan Normal University Open Foundation of Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of the Ministry of Education(Grant No.QSQC2009).
文摘We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided photons.The perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM dynamics.For the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the atom.Our attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian behavior.An asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective single-mode.We also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.
基金supported by the National Natural Science Foundation of China(Grant Nos.11935012,12175052,and 11775065)the Postdoctoral Science Foundation of China(Grant No.2022M722794)。
文摘In quantum open systems,non-Markovianity is an important phenomenon that allows a backflow of information from the environment to the system.In this work,we investigate the non-Markovianity problems in two different types of channels,where the system-environment interactions are treated with and without the rotating-wave approximation(RWA).We employ the quantum interferometric power(QIP)to quantify the non-Markovian dynamics,which is the minimal quantum Fisher information obtained by the local unitary evolution in a bipartite system.By the hierarchy equation method,we calculate the dynamical evolution of the QIP in the non-RWA case.The results show that the dynamical behavior under the non-RWA is significantly different from that under the RWA in both weak and strong coupling.Moreover,in the non-RWA case,we also find the nonmonotonic behavior of the non-Markovianity measure with the variation of coupling strength,which is caused by the competition between the rotating-wave terms and the counterrotating-wave terms.As a result,we highlight the importance of the counterrotating-wave terms for the influence of non-Markovianity.
基金supported by the National Natural Science Foundation of China(Grant No.11075050)the National Key Basic Research Program of China(Grant No.2007CB925204)the Construct Program of the National Key Discipline Ministry of Education of China
文摘We study the non-Markovianity of open qubit systems using the measure N proposed by Breuer, Laine and Piilo [Phys. Rev. Lett. 103 210401 （2009）]. We find that for the three types of quantum noises, amplitude-damping, dephasing and depolarizing noises, there exist some non-Markovian time intervals whose distribution is independent of the selection of the pair of initial states. Therefore, the maximization in the definition of measure N can be actually removed without influencing the detection of non-Markovianity.
基金Project supported by the National Natural Science Foundation of China (Grant No.10864002)
文摘The sudden death of entanglement is investigated for the non-Markovian dynamic process of a pair of interacting flux qubits under a thermal bath. The results show that, for initially two-qubit entangled states, entanglement sudden death （ESD） always happens in the thermal reservoir, where its appearance strongly depends on the environment. In particular, ESD of the qubits occurs more easily for the non-Markovian process than for the Markovian one.
文摘The models of two qubits separately trapped in two independent Markovian or non-Markovian environments have been investigated. The distinction of the two-qubit entanglement dynamics in different environments has also been discussed in detail. The results show that, in non-Markovian environments, the possible usage time of entanglement can be extended due to its memory effect. On the other hand, we note that, compared to Markovian environments, the two-qubit entanglement could be protected better in non-Markovian environments by modulating the detuning between qubits and cavities. Finally, an intuitive physicM interpretation for these results is given.
基金supported by the National Natural Science Foundation of China (Grant No. 11074072)the Innovation Foundation for Postgraduate of Hunan Province of China (Grant No. CX2010B213)
文摘This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values of entanglement can be obtained for an initially factorized state of the two-qubit system. The maximal value of the entanglement increases as the detuning grows. Moreover, the entanglement induced by non-Maxkovian environments is more robust against the asymmetrical couplings between the two qubits and the reservoir. Based on this system, we also show that quantum state transfer can be implemented for arbitrary input states with high fidelity in the non-Markovian regime rather than the Markovian case in which only some particular input states can be successfully transferred.
基金Fundamental Research Funds for the Central Universities,China(Grant No.2018MS056)the National Natural Science Foundation of China(Grant Nos.11605055 and 11974108).
文摘We investigate the non-Markovian effects on the entanglement transfer to the distant non-interacting atom qubits,which are embedded in a coupled superconducting resonator.The master equation governing the dynamics of the system is derived by the non-Markovian quantum state diffusion(NMQSD)method.Based on the solution,we show that the memory effect of the environment can lead to higher entanglement revival and make the entanglement last for a longer time.That is to say,the non-Markovian environment can enhance the entanglement transfer.It is also found that the maximum entanglement transferred to distant atoms can be modified by appropriately selecting the frequency of the modulated intercavity coupling.Moreover,with the initial anti-correlated state,the entanglement between the cavity fields can be almost completely transferred to the separated atoms.Lastly,we show that the memory effect has a significant impact on the generation of entanglement from the initial non-entangled states.
基金supported by the National Natural Science Foundation of China (Grant No 60578055)the State Key Program for Basic Research of China (Grant Nos 2007CB925204 and 2007CB307001)
文摘The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the increase of squeeze parameter r, due to the augmenting of average photon number of every mode in the squeezed vacuum cavity. Second, there appear entanglement revivals after the complete disentanglement for the ease of even parity initial Bell state, while there occur the entanglement decrease and the entanglement revival before the complete disentanglement for the case of odd parity initial Bell state. The results are quite different from those for the case of qubits in a vacuum cavity.
基金supported by the Fundamental Research Funds for the Central Universities,China(Grant Nos.2013-Ia-032 and WUT:2014-Ia-026)
文摘We investigate the time evolution of quantum correlations, which are measured by Gaussian quantum discord in a continuous-variable bipartite system subject to common and independent non-Markovian environments. Considering an initial two-mode Gaussian symmetric squeezed thermal state, we show that quantum correlations can be created during the non-Markovian evolution, which is different from the Markovian process. Furthermore, we find that the temperature is a key factor during the evolution in non-Markovian environments. For common reservoirs, a maximum creation of quantum correlations may occur under an appropriate temperature. For independent reservoirs, the non-Markovianity of the total system corresponds to the subsystem whose temperature is higher. In both common and independent environments, the Gaussian quantum discord is influenced by the temperature and the photon number of each mode.
基金Supported by the National Natural Science Foundation of China under Grant No.10904033Natural Science Foundation of Hubei Province under Grant No.2009CDA145+1 种基金Educational Commission of Hubei Province under Grant No.D20092204the Postgraduate Programme of Hubei Normal University under Grant No.2007D20
文摘We investigate the sudden birth and sudden death of entanglement of two qubits interacting with uncorrelated structured reservoirs. The system is initially prepared in two-qubit extended Werner-like state. We work out the dependence of the entanglement dynamics on both non-Markovian environments and the purity of initial state, and show that non-Markovian environments and the purity can control the time of the two-qubit entanglement sudden death and the reservoirs＇ entanglement sudden birth. Furthermore, under the conditions of different purity and initial entangIement, the revival of qubits＇ entanglement can manifest before, simultaneously or even after the disentanglement of their corresponding reservoirs.
基金Project supported by the National Natural Science Foundation of China(Grant No.11671244)the Research Funds for the Central Universities(Grant Nos.2016TS060 and 2016CBY003)
文摘We investigate the non-Markovian behavior in open quantum systems from an information-theoretic perspective. Our main tool is the max-relative entropy, which quantifies the maximum probability with which a state ρ can appear in a convex decomposition of a state σ. This operational interpretation provides a new view for the non-Markovian process.We also find that max-relative entropy can be the witness and measure of non-Markovian processes. As applications, some examples are also given and compared with other measures in this paper.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304100 and 2016YFA0302700)the National Natural Science Foundation of China(Grant Nos.61327901,11474267,11774335,and 61322506)+5 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDY-SSW-SLH003)the Fundamental Research Funds for the Central Universities,China(Grnat No.WK2470000026)the National Postdoctoral Program for Innovative Talents,China(Grant No.BX201600146)China Postdoctoral Science Foundation(Grant No.2017M612073)Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY020100)the China Scholarship Council(CSC)for financial support(Grant No.10358)
文摘Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies.In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel.We also consider dipole-dipole interactions(DDIs) between the system and ancilla, which are responsible for strong correlations.We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments.We show that DDIs are not only better than detuning at protecting the information(without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics.In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics.In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning.We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10975125 and 11375168)
文摘We study the nonlocal non-Markovian effects through local interactions between two subsystems and the correspond- ing two environments. It has been found that the initial correlations between two environments can turn a Markovian to a non-Markovian regime with extra control on the local interaction time. We further research the nonlocal non-Markovian effects from two situations： without extra control, the nonlocal non-Markovian effects only appear under the condition that two local dynamics are non-Markovian-non-Markovian （both of the two local dynamics are non-Markovian） or Markovian- non-Markovian, but not under the condition of Markovian-Markovian; with extra control, the nonlocal non-Markovian effects can occur under the condition of Markovian-Markovian. It shows that the function of correlations between two environments has an upper bound, which makes a flow of information from the environment back to the global system beginning finitely earlier than that back to one of the two local systems, not infinitely. Then, we proposed two special ways to distribute classical correlations between two environments without initial correlations. Finally, from numerical solutions in the spin star configuration, we found that the self-correlation （internal correlation） of each environment promotes the nonlocal non-Markovian effects.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874099,11605022,11775040,11747317,and 11474044)
文摘The dynamics of two nanospheres nonlinearly coupling with non-Markovian reservoir is investigated. A master equation of the two nanospheres is derived by employing quantum state diffusion method. It is shown that the nonlinear coupling can improve the non-Markovianity. Due to the sharing of the common non-Markovian environment, the state transfer between the two nanospheres can be realized. The entanglement and the squeezing of the individual mode, as well as the jointed two-mode are analyzed. The present system can be realized by trapping two nanospheres in a wideband cavity, which might provide a method to study adjustable non-Markovian dynamics of mechanical motion.
基金supported by the Science and Technology Plan of Hunan Province,China(Grant No.2010FJ3148)the National Natural Science Foundation of China(Grant No.11374096)
文摘The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275064 and 11075050)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20124306110003)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in Universities of China(Grant No.IRT0964)the Construct Program of the National Key Discipline
文摘We study the entanglement （measured by negativity） evolution and the non-Markovianity for the dynamical process of a spin-S system embedded in dephasing environments. The exact analytical solution is presented, which shows that the decoherence function governs the evolutions of coherence, entanglement, and the non-Markovianity of the correspond- ing dynamical processes. For Ohmic and sub-Ohmic reservoirs, the negativity decreases monotonically in time and the corresponding dynamics is Markovian. While for super-Ohmic reservoirs with non-monotonic decoherence function, the negativity appears as the phenomenon of revival and the corresponding dynamics is non-Markovian. The relation between non-Markovianity and the system dimension is studied.
文摘Preventing quantum entanglement from decoherence effect is of theoretical and practical importance in the quantum information processing technologies.In this regard,we consider the entanglement dynamics of two identical qubits where the qubits which are coupled to two independent（Markovian and/or non-Markovian） as well as a common reservoir at zero temperature are further interacted with a classical driving laser field.Then,we study the preservation of generated two-qubit entanglement in various situations using the concurrence measure.It is shown that by applying the classical driving field and so the possibility of controlling the Rabi frequency,the amount of entanglement of the two-qubit system is improved in the off-resonance condition between the qubit and the central cavity frequencies（central detuning） in both non-Markovian and Markovian reservoirs.While the central detuning has a constructive role,the detuning between the qubit and the classical field（laser detuning） affects negatively on the entanglement protection.The obtained results show that long-living entanglement in the non-Markovian reservoir is more accessible than in the Markovian reservoir.We demonstrate that,in a common reservoir non-zero stationary entanglement is achievable whenever the two-qubit system is coupled to the reservoir with appropriate values of relative coupling strengths.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275064 and 11075050)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20124306110003)the Construct Program of the National Key Discipline,China
文摘We present a paradigmatic method for exactly studying non-Markovian dynamics of a multi-level V-type atom interacting with a zero-temperature bosonic bath. Special attention is paid to the entanglement evolution and the dynamical nonMarkovianity of a three-level V-type atom. We find that the entanglement negativity decays faster and non-Markovianity is smaller in the resonance regions than those in the non-resonance regions. More importantly, the quantum interference between the dynamical non-Markovianities induced by different transition channels is manifested, and the frequency domains for constructive and destructive interferences are found.
基金Project supported by the National Natural Science Foundation of China(Grant No.11075101)
文摘We study the non-Markovianity of the single qubit system coupled with an isotropic Lipkin-Meshkov-Glick（LMG）model by an effective method proposed by Breuer et al.（Breuer H P and Piilo J 2009 Europhys. Lett. 85 5004）. It is discovered that the non-Markovianity is concerned with the quantum phase transitions（QPTs）. In the open system, we present that the strong coupling inside the bath and the strong interaction between the system and bath can enhance the degree of non-Markovianity. Moreover, the non-Markovianity is stronger and more sensitive for the bath in the symmetric phase than the symmetry broken phase.
