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1.
A system consisting of two different atoms interacting with a two-mode vacuum, where each atom is resonant only with one cavity mode, is considered. The effects of dipole-dipole (dd) interaction between two atoms on the atom-atom entanglement and mode--mode entanglement are investigated. For a weak dd interaction, when the atoms are initially separable, the entanglement between them can be induced by the dd interaction, and the entanglement transfer between the atoms and the modes occurs efficiently; when the atoms are initially entangled, the entanglement transfer is almost not influenced by the dd interaction. However, for a strong dd interaction, it is difficult to transfer the entanglement from the atoms to the modes, but the atom-atom entanglement can be maintained when the atoms are initially entangled. 相似文献
2.
Extending the double Jaynes--Cummings model to a more
complicated case where the mode--mode competition is considered, we
investigate the entanglement character of two isolated atoms by
means of concurrence, and discuss the dependence of atom--atom
entanglement on the different initial state and the relative
coupling strength between the atom and the corresponding cavity
field. The results show that the amplitude and the period of the
atom--atom entanglement evolution can be controlled by the choice of
initial state and relative coupling strength, respectively. We find
that the phenomenon of entanglement sudden death (ESD) is sensitive
to the initial conditions. The length of the time interval for
zero entanglement depends not only on the initial degree of
entanglement between two atoms but also on the relative coupling
strength of atom--field interaction. The ESD effect can be weakened
by enhancing the mode--mode competition between the three- and
single-photon processes. 相似文献
3.
We investigate the entanglement dynamics of a system composed of two non-interacting qubits, A and B. A third qubit, C, only has the Dzyaloshinskii-Moriya (DM) spin-orbit interaction with qubit B. We find that the DM interaction can induce the entanglement sudden death (ESD) of the system qubits A and B, and properly mixing the initial state of the system and adjusting the state of qubit C are two effective methods of controlling ESD. 相似文献
4.
We investigate the entanglement dynamics of two initially entangled atoms each interacting with a thermal field.We show that the two entangled atoms become completely disentangled in a finite time and that the lost information cannot return to the atomic system when the mean photon number of the thermal field exceeds a critical value (3.3584),even though the whole system is lossless.Then we study how the detuning between the atomic transition frequency and the field frequency and the disparity between two coupling rates would affect the evolution of the entanglement of the atomic system. 相似文献
5.
In this paper, we study the entanglement dynamics of two-spin
Heisenberg XYZ model with the Dzialoshinskii--Moriya (DM)
interaction. The system is initially prepared in the Werner state.
The effects of purity of the initial state and DM coupling parameter
on the evolution of entanglement are investigated. The necessary and
sufficient condition for the appearance of the entanglement sudden
death (ESD) phenomenon has been deduced. The result shows that the
ESD always occurs if the initial state is sufficiently impure for
the given coupling parameter or the DM interaction is sufficiently
strong for the given initial state. Moreover, the critical values of
them are calculated. 相似文献
6.
We investigate the entanglement dynamics of a system composed of two non-interacting qubits,A and B.A third qubit,C,only has the Dzyaloshinskii-Moriya(DM)spin-orbit interaction with qubit B.We find that the DM interaction can induce the entanglement sudden death(ESD)of the system qubits A and B,andproperly mixing the initial state of the system and adjusting the state of qubit C are two effective methods of controlling ESD. 相似文献
7.
The entanglement of two dipole--dipole coupled atoms interacting with a thermal field via a two-photon process
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This paper studies entanglement between two dipole-dipole coupled atoms interacting with a thermal field via a two-photon process. It shows that the entanglement is dependent on the mean photon number of the thermal field and the dipole-dipole interaction. The results also show that the atom-atom entanglement through the two-photon process is larger than that through the one-photon process and a remarkable amount of entanglement between the atoms still remains at certain times even for a very highly noisy thermal field. 相似文献
8.
This paper presents a treatment of the entanglement
transfer between atoms in two distant cavities coupled by an optical
fibre. If the atoms resonantly and collectively interact with the
local single-mode cavity fields and the dipole--dipole interaction
between the atoms is neglected, then it shows that a complete
transfer of entanglement from one pair of atoms to another can be
deterministically realized. Furthermore, it also investigates the
effects of dipole--dipole interaction on entanglement transfer on
the condition that the interaction between the atoms and the cavity
is much weaker than the coupling between the cavity and the fibre. 相似文献
9.
10.
Exact solution of entanglement of the double Jaynes-Cummings model without rotating wave approximation
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This paper investigates the influences of atom-field coupling and dipole-dipole coupling for atoms on the entanglement between two atoms by means of concurrence. The results show that the sudden death occurs when the atom-field coupling is strong enough, and the collapse and the revival appear when the dipole-dipole interaction is strong enough. 相似文献
11.
Entanglement sudden death of two atoms interacting with a cavity via the two-photon process in a strong-driving-assisted system
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We examine the entanglement dynamics between two strongly
driven atoms off-resonantly coupled with a single-mode cavity via
the two-photon process with the help of negativity in two different
types of initial states. The results show that entanglement sudden
death may occur under both the above conditions and the sudden death
effect can be monitored by modulating the atom--cavity detunings.
Furthermore, we also find an atomic decoherence-free subspace so
that the initial entanglement between two atoms remains invariable
in application. 相似文献
12.
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
13.
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
14.
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
15.
This paper investigates the periodic death and anabiosis of the entanglement between two moving atoms interacting with the mode field, and discusses the influences of the atomic motion and the parameter of the mode field. The results show that, the atomic motion leads to the periodic death and anabiosis of the entanglement between two moving atoms, the time of the death and the amplitude of the anabiosis of the entanglement between two moving atoms depend on the initial states of two moving atoms and the parameter of the mode field. 相似文献
16.
本文研究了频率随时间变化的光场对双J-C模型中原子--原子纠缠的动力学调控, 主要讨论了光场频率随时间作正弦变化和脉冲变化两种典型情况下, 原子--原子纠缠度随时间的演化特性. 当光场频率随时间作正弦变化时, 原子--原子纠缠度演化的周期、振幅与光场频率调制的振幅有关, 并随着调制振幅的增强而减小. 光场频率的正弦调制和脉冲调制均能使光场与原子的相互作用模式在共振和非共振之间发生变化, 直接影响原子--原子纠缠度的演化规律. 通过光场频率的调制可以实现原子--原子纠缠度的提高与稳定, 避免ESD现象的出现, 从而达到动态调控原子--原子纠缠的目的. 相似文献
17.
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
18.
Qi-Liang He 《Optics Communications》2011,284(6):1714-1718
We investigate the entanglement dynamics and the phenomenon of entanglement sudden death in the two-photon Tavis-Cummings model with an added nonlinear kerr-like medium. It is shown that the phenomenon of entanglement sudden death can be controlled by the nonlinear kerr-like medium. Furthermore, the influence of dipole-dipole interaction on entanglement between atoms is also discussed. It is found that the phenomenon of entanglement sudden death can be weakened by the dipole-dipole interaction. Finally, we investigate the influence of kerr medium and dipole-dipole interaction on the three-partite entanglement of the system by making use of the state preparation fidelity. 相似文献
19.
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
20.
Relation between initial conditions and entanglement sudden death for two-qubit extended Werner-like states
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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