共查询到18条相似文献,搜索用时 140 毫秒
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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
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研究了初始处于GHZ态的三个两能级原子与双模腔场相互作用系统的纠缠动力学特性,得到了并发度和线性熵的解析表达式.讨论了腔场初始纠缠度对腔内两原子之间纠缠的影响,对其余子系统求迹后结果表明腔内两原子之间的纠缠出现突然产生现象,腔内两原子之间产生纠缠的阈值时间和最大值依赖于双模腔场初始纠缠度;并且发现腔内两原子子系统和腔外原子与场子系统之间在整个的时间演化过程中一直保持着纠缠状态. 相似文献
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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
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两原子与数态场相互作用系统中纠缠的调控 总被引:1,自引:1,他引:0
通过计算并发度研究了两个处于初始激发态的两能级原子与数态场相互作用系统的纠缠动力学特性,并讨论了场的光子数、原子和场的失谐量以及原子操作对并发度的影响。结果表明当不存在原子操作时,两原子之间的纠缠出现突然产生现象,并且可以通过调节光子数和原子与场的失谐量来控制产生纠缠的阈值时间和纠缠的最大值。当存在原子操作时,两原子之间的纠缠随着时间的演化可以立即产生,而且通过对经典场的操作和控制可以实现两原子之间纠缠的调控。 相似文献
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三个两能级原子与数态场相互作用的纠缠特性 总被引:1,自引:1,他引:0
通过计算并发度和线性熵研究了初始处于GHZ态的三个两能级原子与数态场相互作用系统的纠缠动力学特性,讨论了场的初始光子数对并发度和线性熵的影响.结果表明,腔内两原子之间的纠缠出现突然产生现象,而且可以通过改变场的初始光子数来控制产生纠缠的阈值时间和纠缠的最大值.对腔外原子的探测导致了并发度随时间的演化呈现周期性规律,场的光子数的增加不但减小了并发度的最大值,而且缩短了并发度的演化周期. 相似文献
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初始处于纠缠的原子与附加类克尔介质的光腔相互作用,运用共生纠缠的度量方法对原子间的纠缠演化动力学进行研究,分析了腔场粒子数、介质非线性效应及原子与腔场的失谐量对纠缠演化的影响,发现处于腔场真空态下原子间的纠缠作周期性震荡演化,而处在腔场粒子数态下的原子在演化过程中发生纠缠突然死亡现象;在非线性克尔介质作用下,处于腔场粒子数较小范围内(n≤5)的原子间也会产生纠缠突然死亡现象;但随着腔场粒子数的增加纠缠突然死亡现象消失而且一定程度上可以达到纠缠初始值;当腔场处于任意粒子数态时,由于非线性效应的影响,均可抑制纠缠突然死亡现象的发生;当腔场在没有类克尔介质作用时,原子与腔场间的失谐量同样可以避免纠缠突然死亡现象的发生. 相似文献
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通过计算并发度和线性熵研究了初始处于GHZ态的三个两能级原子与数态场相互作用系统的纠缠动力学特性,讨论了场的初始光子数对并发度和线性熵的影响.结果表明,腔内两原子之间的纠缠出现突然产生现象,而且可以通过改变场的初始光子数来控制产生纠缠的阈值时间和纠缠的最大值.对腔外原子的探测导致了并发度随时间的演化呈现周期性规律,场的光子数的增加不但减小了并发度的最大值,而且缩短了并发度的演化周期. 相似文献
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Sudden birth versus sudden death of entanglement for the extended Werner-like state in a dissipative environment 下载免费PDF全文
In this paper, we investigate the dynamical behaviour of
entanglement in terms of concurrence in a bipartite system
subjected to an external magnetic field under the action of
dissipative environments in the extended Werner-like initial state.
The interesting phenomenon of entanglement sudden death as well as
sudden birth appears during the evolution process. We analyse in
detail the effect of the purity of the initial entangled state of two qubits
via Heisenberg XY interaction on the apparition time of entanglement
sudden death and entanglement sudden birth. Furthermore, the
conditions on the conversion of entanglement sudden death and
entanglement sudden birth can be generalized when the initial
entangled state is not pure. In particular, a critical purity of the
initial mixed entangled state exists, above which entanglement
sudden birth vanishes while entanglement sudden death appears. It is
also noticed that stable entanglement, which is independent of
different initial states of the qubits (pure or mixed state), occurs
even in the presence of decoherence. These results arising from the
combination of the extended Werner-like initial state and dissipative
environments suggest an approach to control and enhance the
entanglement even after purity induced sudden birth, death and
revival. 相似文献
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A system consisting of two atoms interacting with a
two-mode vacuum is considered, where each atom is resonant with the
two cavity modes through two different competing transitions. The
effect of mode--mode competition on the atom--atom entanglement is
investigated. We find that the entanglement between the two atoms
can be induced by the mode--mode competition. For the initial atomic
state |\varPsi(0)\rangle, whether the atoms are initially
separated or entangled, a large or even maximal entanglement between
them can be obtained periodically by introducing the mode--mode
competition. For the initial atomic state |\varPhi(0)\rangle, the
strong mode--mode competition can prevent the two atoms entangled
initially from suffering entanglement sudden death; besides, it
makes them in a more stable and longer-lived entanglement than in
the non-competition case. 相似文献
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In this paper, we study the entanglement dynamics of atoms
locally coupled to a cavity field. By studying two different models
within the framework of cavity QED, we show that the so-called
atomic entanglement sudden death always occurs if initially the
cavity field is in the thermal state, in clear contrast with that in
the vacuum state where the same entanglement decay is in infinite
time. 相似文献
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We investigate the entanglement dynamics via the concurrence of two distant atoms interacting off-resonantly with two cavity fields in Fock states,respectively.We find that the evolution of entanglement has sudden death and sudden birth phenomena,that with the increase of photon numbers in the two cavities,the alternate frequency of sudden death and sudden birth turns fast,and that the amplitude of concurrence oscillates regularly with oscillation frequency becoming slow when the cavity fields have the same photon numbers.While,the maximum of concurrence declines and the amplitude of concurrence oscillates irregularly when the two cavity fields have different photon numbers.In addition,we find the length of death time is dependent on the initial entanglement. 相似文献
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Quantum correlations between two non-interacting atoms under the influence of a thermal environment 下载免费PDF全文
By considering a double Jaynes-Cummings model, we investigate the dynamics of quantum correlations, such as the quantum discord and the entanglement, for two atoms in their respective noisy environments, and study the effect of the purity and the cavity temperature on the quantum correlations. The results show that the entanglement suffers sudden death and revival, however the quantum discord can still reveal the quantum correlations between the two atoms in the region where the entanglement is zero. Moreover, when the temperature of each cavity is high the entanglement dies out in a short time, but the quantum discord still survives for quite a long time. It means that the quantum discord is more resistant to environmental disturbance than the entanglement at higher temperatures. 相似文献
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In this paper the so-called sudden death effect of entanglement is
investigated in a quantum model. The results show that one can
expect the resurrection of the original entanglement to occur in a
periodic way following each sudden death event. The length of the
time interval for the zero entanglement depends not only on the
degree of entanglement of the initial state but also on the initial
state. 相似文献
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The entanglement of two moving atoms interacting with a single-mode field via a three-photon process 下载免费PDF全文
In this paper, the entanglement of two moving atoms
induced by a single-mode field via a three-photon process is
investigated. It is shown that the entanglement is dependent on the
category of the field, the average photon number N, the number p
of half-wave lengths of the field mode and the atomic initial state.
Also, the sudden death and the sudden birth of the entanglement are
detected in this model and the results show that the existence of the
sudden death and the sudden birth depends on the parameter and the
category of the mode field. In addition, the three-photon process is a higher
order nonlinear process. 相似文献