共查询到20条相似文献,搜索用时 46 毫秒
1.
SHAN Chuan-Jia LIU Ji-Bing CHEN Tao CHENG Wei-Wen LIU Tang-Kun HUANG Yan-Xia LI Hong 《理论物理通讯》2010,54(3):427-432
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 entanglement, the revival of qubits' entanglement can manifest before, simultaneously or even after the disentanglement of their corresponding reservoirs. 相似文献
2.
SHAN Chuan-Jia LIU Ji-Bing CHENG Wei-Wen LIU Tang-Kun HUANG Yan-Xia LI Hong 《理论物理通讯》2009,51(6):1013-1016
In this paper, we study entanglement dynamics of a two-qubit extended Werner-like state locally, interacting with independent noisy channels, i.e., amplitude damping, phase damping, and depolarizing channels. We show that the purity of initial entangled state has direct impacts on the entanglement robustness in each noisy channel. That is, if the initial entangled state is prepared in mixed instead of pure form, the state may exhibit entanglement sudden death (ESD) and/or be decreased for the critical probability at which the entanglement disappear. 相似文献
3.
Xiu-Xing Zhang Guang-Hou Sun Xun-Chang Yin Chuan-Jia Shan 《International Journal of Theoretical Physics》2010,49(6):1212-1221
We investigate entanglement dynamics and transfer in a system of two identical independent qubits, each of them locally interacting
with a bosonic reservoir. Starting from two-qubit extended Werner-like states, we have shown that the degree of entanglement
of the initial states, Markovian environments and the purity can control the time of the two-qubit entanglement sudden death
and the reservoirs’ entanglement sudden birth. Moreover, the phenomenon of entanglement sudden death/birth may occur depending
on the values of parameters like purity or degree of entanglement of the initial state. When initial states are not pure,
entanglement sudden death/birth always occurs, this will permit us to link the occurrence time of entanglement sudden death/birth
and entanglement transfer to the purity or the degree of entanglement of the initial states. 相似文献
4.
Chuan-Jia Shan Tao Chen Ji-Bing Liu Wei-Wen Cheng Tang-Kun Liu Yan-Xia Huang Hong Li 《International Journal of Theoretical Physics》2010,49(4):717-727
The decoherence and the decay of quantum entanglement due to both population relaxation and thermal effects are investigated
for the two qubits initially prepared in the extended Werner-like state by solving the Lindblad form of the master equation,
where each qubit is interacting with an independent reservoir at finite temperature T. Entanglement sudden death (ESD) and entanglement sudden birth (ESB) are observed during the evolution process. We analyze
in detail the effects of the mixedness, the degree of entanglement of the initial states and finite temperature on the time
of entanglement sudden death and entanglement sudden birth. We also obtain an analytic formula for the steady state concurrence
that shows its dependence on both the system parameters, the decoherence rate and finite temperature. These results arising
from the combination of extended Werner-like initial state and independent thermal reservoirs suggest an approach to control
the maximum possible concurrence even after the purity and finite temperature induce sudden birth, death and revival. 相似文献
5.
研究了初态为X态时Tavis-Cummings模型中具有偶极相互作用两原子的纠缠演化特性,在演化过程中,同时号码出现了两原子的纠缠突然死亡(ESD)与突然产生(ESB)两种有趣的现象.详细分析了两原子初始态的纯度、偶极相互作用、光场粒子数对这两种现象出现时间的影响,进一步给出了初始为混态时ESB与ESD的转换条件.计算结果表明,上述系统参量对两原子的纠缠演化、ESB与ESD有重要的影响,偶极相互作用会改变纠缠度的振荡周期,使出现ESD的时间间隔减少;随着初始两原子纠缠纯度的增大,纠缠突然产生以及纠缠突然死亡存在的时间缩短,并且可以提高两原子之间的纠缠;对于特殊的初态,产生了纠缠不变性以及固定的两原子纠缠,该定值受两原子初始状态的纯度控制。 相似文献
6.
In this paper, we consider the entanglement dynamics of a four-qubit model [2006 Phys. Rev. A 74 042328] where two entangled qubits a and b locally interact with separate qubits A and B via the spin-exchange-like Hamiltonian. We study the effect of purity of initial entangled state of qubits a, b on the entanglement evolution and its relation with energy transfer. Also, we find that the total bipartite entanglement of qubits a, b plus A, B is not a constant any longer when the initial entangled state of a, b is not pure, which is a complement to the result in the paper [2007 J. Phys. B 40 S45] for the pure case. 相似文献
7.
Relation between initial conditions and entanglement sudden death for two-qubit extended Werner-like states 下载免费PDF全文
In this paper, the dynamical behavior of entanglement of an uncoupled two-qubit system, which interacts with inde- pendent identical amplitude damping environments and is initially prepared in the extended Werner-like (EWL) states, is investigated. The results show that whether entanglement sudden death (ESD) of an EWL state will occur or not depends on initial purity and concurrence. The boundaries between ESD states and ESD-free states for two kinds of EWL states are found to be different. Furthermore, some regions are shown where ESD states can be transformed into ESD-free states by local unitary operations. 相似文献
8.
Smail Bougouffa 《Optics Communications》2010,283(14):2989-2996
An experimental scheme is suggested that permits a direct measure of entanglement in a two-qubit cavity system. It is realized in the cavity-QED technology utilizing atoms as flying qubits. With this scheme we generate two different measures of entanglement, namely logarithmic negativity and concurrence. The phenomenon of sudden death entanglement (ESD) in a bipartite system subjected to dissipative environment is examined. We show that the sudden death time of the entangled states depends on the initial preparation of the entangled state and the temperature of the reservoir. 相似文献
9.
We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state. 相似文献
10.
ZOU Jian CAI Jin-Fang SHAO Bin LI Qian-Shu 《理论物理通讯》2005,44(2):259-268
We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state. 相似文献
11.
The entanglement of two atomic qubits, which are coupled to a coherent state field with different couplings, is studied. The dynamical evolution of the concurrence, which measures the degree of the entanglement between the two qubits, is plotted versus the scaled
time gt. It is found that the two qubits can be entangled by the coherent state field even when they are initially prepared in the most mixed state, and for very weak field, the most mixed state can be more easily entangled than some pure
states. It is also found that the entanglement between the qubits sensitively depends on the relative difference of the atomic couplings and the mean photon number of the field. 相似文献
12.
Entanglement evolution of three-qubit mixed states in multipartite cavity—reservoir systems 下载免费PDF全文
We analyze the multipartite entanglement evolution of three-qubit mixed states composed of a GHZ state and a W state.For a composite system consisting of three cavities interacting with independent reservoirs,it is shown that the entanglement evolution is restricted by a set of monogamy relations.Furthermore,as quantified by the negativity,the entanglement dynamical property of the mixed entangled state of cavity photons is investigated.It is found that the three cavity photons can exhibit the phenomenon of entanglement sudden death(ESD).However,compared with the evolution of a generalized three-qubit GHZ state which has the equal initial entanglement,the ESD time of mixed states is later than that of the pure state.Finally,we discuss the entanglement distribution in the multipartite system,and point out the intrinsic relation between the ESD of cavity photons and the entanglement sudden birth of reservoirs. 相似文献
13.
研究了两个初始处于纠缠相干态上的宏观场各自独立地与一个环境相互作用的系统, 环境对腔场的影响只体现在腔场光子数的泄漏上. 采用共生纠缠(concurrence)度量两个宏观场间的纠缠, 并给出宏观场纠缠的解析解, 以分析这种系统中宏观场纠缠的动力学特性. 研究表明当场的初始平均光子数较大时, 即使很小的光子泄漏率也会导致腔场间出现纠缠突然死亡现象. 同时研究结果也表明光子从腔场泄漏到环境后会导致两环境间的纠缠突然产生, 而这种纠缠产生的时机直接与腔场的初始光子数相关. 本文还进一步发现在大光子数的情况下, 在任何时刻任意一个腔场与任意一个环境间都不会产生纠缠.
关键词:
纠缠相干态
环境
纠缠突然死亡
纠缠突然产生 相似文献
14.
References: 《理论物理通讯》2007,47(4):621-624
We investigate the entanglement transfer in a four-qubit system and calculate the concurrence between any two qubits in different initial states. We show that both the pure entangled state and mixed entangled state can be transferred. For some special coupling constants and some evolution time, entanglement can be completely transferred from one pair particles to another. 相似文献
15.
Avoiding the decay of entanglement for coupling two-qubit system interacting with a non-Markov environment 下载免费PDF全文
The entanglement evolution of the coupled qubits interacting with a non-Markov environment is investigated in terms of concurrence.The results show that the entanglement of the quantum systems depends not only on the initial state of the system but also on the coupling between the qubit and the environment.For the initial state (|00 ± |11) /21/2,the coupled qubits will always been in the maximum entangled state under an asymmetric coupling.For the initial state (|01 ± |10) /21/2,in contrast,the entangling degree of the coupled qubits is always equal to unity and does not depend on the evolving time under the symmetric coupling.We find that the stronger the interaction between the qubits is,the better the struggle against the entanglement sudden death is. 相似文献
16.
A.-B. A. Mohamed 《International Journal of Theoretical Physics》2012,51(9):2779-2786
Quantumness of the correlations between two qubits, coupled to a cavity field whenever the system is open or closed, is investigated when sudden death (or birth) of the entanglement occurs. It is found that quantum correlation not exists only in the entangled state. It’s found that the dephasing parameters and the purity of the initial states play an important role in the dynamics behaviors of the quantum correlations, including entanglement. Quantumness of the correlations and entanglement, due to dephasing of the cavity, are damped until the same their values which are contained in their initial states. 相似文献
17.
We study the entanglement dynamics between two strongly-AC-driven superconducting charge qubits coupled collectively to a zero temperature, dissipative resonator and find an unusual feather that the competing of creation and annihilation of entanglement can lead to entanglement increasing, sudden death and revival. We also calculate the dependence of the death time on the initial state of the system. 相似文献
18.
19.
J. Li G. S. Paraoanu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(2):255-264
We analyze a system of two qubits embedded in two different environments. The qubits are coupled to each other and driven
on-resonance by two external classical sources.
In the secular limit, we obtain exact analytical results for the evolution of the system for several classes of two-qubit
mixed initial states. For Werner states we show that the decay of entanglement does not depend on coupling. For other initial
states with “X"-type density matrices we find that the sudden death time displays a rich dependence on the coupling energy and state parameters
due to the existence of processes of delayed sudden birth of entanglement. 相似文献
20.
We have studied entanglement evolution and transfer in a double
Tavis--Cumming model where two pairs of entangled two-level atoms
AB and CD interact with two single-mode cavity fields a and
b. We show that the Bell-like initial state of atoms AB can
exhibit entanglement sudden death which should be independent of the
initial entanglement of atoms CD. Also, we show that the initial
entanglement of one atomic pair can be transferred into another
pair, as well as the possible subsystems, that become entangled
during evolution. 相似文献