共查询到20条相似文献,搜索用时 31 毫秒
1.
《中国物理快报》2016,(7)
We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice.Starting from an unentangled initial state associated with the regular 'island' of classical phase space,it is demonstrated that the quantum resonance leads to entanglement generation,the chaotic parameter region results in the increase of the generation speed,and the symmetries of the initial probability distribution determine the final degree of entanglement.The entangled initial states are associated with the classical 'chaotic sea',which do not affect the final entanglement degree for the same initial symmetry.The results may be useful in engineering quantum dynamics for quantum information processing. 相似文献
2.
We investigate the entanglement swapping of continuous state and the two-mode squeezed vacuum which is exposed variable using the pair coherent state as the input in a phase decoherence environment as the quantum channel. By adopting the log-negativity as the measure of entanglement, we analyze how entanglement of the two initial states and the phase decoherence environment affect the entanglement swapping quality. 相似文献
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We investigate the dependence of phase sensitivity and entanglement of two streams of photons that they incident upon Mach-Zehnder interferometer on the initial input states and the phase difference. Phase sensitivity and entanglement are periodic function of the phase difference. The initial input state with the more photons or smaller population difference induces the better phase sensitivity and entanglement. 相似文献
5.
We study entanglement teleportation in the two‐qubit XX Heisenberg model with pure phase decoherence taken into account. For some initial entangled states, pure phase decoherence has no effect on the teleported entanglement, while for others pure phase decoherence has a pronounced effect. In addition, entanglement sudden death happens in the latter case. 相似文献
6.
Sudden Death of Entanglement between Two Atoms with Initial Tripartite Entangled State in the Tavis--Cummings Model
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We study the entanglement dynamics of two atoms with initial tripartite entangled W-like state in the Tavis-Cummings model. We find that the entanglement evolvement is sensitive not only to the entanglement degree of the initial state but also to the concrete form of the initial state. The so-called sudden death effect occurs only for some initial states. 相似文献
7.
The influence of white and color noise on the outcome of the entanglement swapping process is investigated in a four-qubit system. Critical degree of noise in initial state, that could destroy entanglement in a result state is presented. The entanglement characteristics, such as concurrence, tangle, etc. are compared. Results could be helpful for experiments regarding entanglement swapping as conditions for initial quantum entangled states, to obtain entangled result state. 相似文献
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Guo Hui Yang Xiang Yang Miao Jun Feng Zhang 《International Journal of Theoretical Physics》2010,49(4):766-776
We report possibility of generating entanglement and steady entanglement between two identical atoms in free space with a
very natural way when their spatial separation is on the order of wavelength or less. We show a dynamical creation of entanglement
and steady entanglement due to the radiative coupling with different separable initial atomic states and study the entanglement
properties about this atomic subsystem. Not only the creation of steady state entanglement is decided by the initial atomic
states, but also the magnitude of the entanglement and the steady state entanglement are found to be strongly dependent on
the initial states. We derive a master equation for the atomic subspace and solve it analytically to show how the spontaneous
emission from the two atoms system induces entanglement and steady entanglement, the crossing coupling terms in master equation
can enhance the entanglement value. 相似文献
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With the consideration of three-body interaction, dynamics of pairwise entanglement in spin chains is studied. The dependence of pairwise entanglement dynamics on the type of coupling, and distance between the spins is analyzed in a finite chain for different initial states. It is found that, for an Ising chain, three-body interactions are not in favor of preparing entanglement between the nearest neighbor spins, while three-body interactions are favorable for creating entanglement between remote spins from a separable initial state. For an isotropic Heisenberg chain, the pairwise concurrence will decrease when three-body interactions are considered both for a separable initial state and for a maximally entangled initial state, however, three-body interactions will retard the decay of the concurrence in an Ising chain when the initial state takes the maximally entangled state. 相似文献
12.
Quantum entanglement dynamics of two Tavis-Cummings atoms interacting with the quantum light sources in a cavity is investigated. The results show the phenomenon that the concurrence disappears abruptly in a finite time, which depends on the initial atomic states and the properties of squeezed states. We find that there are two decoherence-free states in squeezed vacuum fields: one is the singlet state, and the other entangled state is the state
that combines both excited states and ground states with a relative phase being equal to the phase of the squeezed state. 相似文献
13.
根据单量子比特的映射, 提出一个在有限温度下运用弱测量保护两量子比特纠缠的方案. 在两个可通过局域幺正变化实现的等价的初始纠缠进入广义振幅阻尼信道前后, 对其分别进行弱测量, 并对四个弱测量的参数做全面的优化, 获取最大共生纠缠Cr 和弱测量参数m, n的解析表达式, 然后再进一步研究弱测量参数与信道参数的关系. 发现这种基于弱测量的纠缠保护方法在某些情况下可以有效地提高纠缠, 甚至可以避免纠缠的突然死亡. 当信道参数r一定时, 对不同的参数p,初始态|ψ>纠缠达到最大值时对应的弱测量参数m的取值一样, 共生纠缠关于p=0.5对称, 而初始态|φ>对应的参数m的取值不同; 在参数p一定、参数r不同、初始态|ψ>或|φ>的情况下, 当纠缠度取最大值时, 弱测量参数m的取值不变, 且随着r的增加, 纠缠度减少. 通过对信道参数的分析, 发现可以选择合适的信道参数和初始态来获得较大的纠缠. 相似文献
14.
We analyze the effect of the quantum noise of an amplifier on the entanglement properties of an input state. We consider both phase insensitive and phase sensitive amplification and specialize to Gaussian states for which entanglement measures are well developed. In the case of phase insensitive amplification in which both the modes are symmetrically amplified, we find that the entanglement in the output state vanishes if the intensity gain exceeds a limiting value 2/(1+exp[-EN]) where EN is the logarithmic negativity of the input state which quantifies the initial entanglement between the two modes. The entanglement between the two modes at the output is found to be more robust if only one mode is amplified. 相似文献
15.
Temporal evolution is studied for total entropy, the entropy difference and the sum of negative eigenvalues of the partially transposed density matrix as quantitative entanglement measurements for JC model in a phase-damped cavity in the dispersive approximation. The cavity field is assumed to be coupled to a reservoir with a phase-damping coupling. The case of a statistical mixture (SM) of coherent states is considered as initial field state. The effects of cavity phase damping on the entanglement between the field and the atom are studied. 相似文献
16.
R. Safaiee M. M. Golshan 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(4):457-463
The present work is concerned with an analysis of the entanglement between the electronic
coherent superpositions of spin states and subbands in a
quasi-one-dimensional Rashba nanoloop acted upon by a strong perpendicular magnetic field.
We explicitly include the confining potential and the Rashba spin-orbit coupling into the
Hamiltonian and then proceed to calculate the von Neumann entropy, a measure of
entanglement, as a function of time. An analysis of the von Neumann entropy demonstrates
that, as expected, the dynamics of entanglement strongly depends upon the initial state
and electronic subband excitations. When the initial state is a pure one formed by a
subband excitation and the z-component of spin states, the entanglement exhibits periodic
oscillations with local minima (dips). On the other hand, when the initial state is formed
by the subband states and a coherent superposition of spin states, the
entanglement still periodically oscillates, exhibiting stronger correlations, along with
elimination of the dips. Moreover, in the long run, the entanglement for the latter case
undergoes the phenomenon of collapse-revivals. This behaviour is absent for the first case
of the initial states. We also show that the degree of entanglement strongly depends upon
the electronic subband excitations in both cases. 相似文献
17.
The dynamical properties of quantum entanglement in the integrable Jaynes-Cummings model with a Kerr nonlinearity are studied in terms of the reduced-density linear entropy with various Kerr coupling parameters and initial states, where the initial states are prepared by the coherent states placed in the corresponding phase space described in terms of canonical variables. The mean entanglement averaged over time is employed to investigate the behavior of entanglement of those coherent states. It is shown that the mean entanglement of the coherent states put near the centers of periodic orbits, both with a strong Kerr coupling and without a Kerr coupling, tends to be the minimal, and that the mean entanglement of the coherent states centered near the boundary with a strong Kerr coupling is the minimal while that without Kerr coupling is the maximal. 相似文献
18.
Finding the most robust entangled states during the whole process of decoherence is a particularly fundamental problem for quantum physics and quantum information processing. In this paper, the decoherence process of two-qubit system under two individual identical decoherence channels is investigated systematically. We find that although the robustness of two-qubit states with same initial entanglement is usually different, the Bell-like states are always the most robust entangled states during decoherence. That is to say, affected by the same amount of noise, the remain entanglement of an arbitrary two-qubit state is not more than that of a Bell-like state with the same initial entanglement. 相似文献
19.
Bell态原子与双模纠缠相干光场相互作用的纠缠特性 总被引:1,自引:0,他引:1
运用Negativity熵研究了Bell态原子与双模纠缠相干光场相互作用系统中两个全同二能级原子之间的纠缠演化特性.分析了光场强度、光场纠缠度及原子间相互作用强度对纠缠的影响.结果表明:原子处于|β11〉时,两原子始终处于最大纠缠态;原子处于|β00〉时,初始纠缠的两原子始终较长时间处于退纠缠状态;原子处在|β10〉时,增大双模光场的平均光子数可以明显增大两原子之间的纠缠度并保持较大的纠缠状态;原子初态处在|β01〉时,原子间的相互作用强度对双原子间纠缠度有较显著的非线性调制作用. 相似文献
20.
Xi-Wen Hou Ming-Fang Wan Zhong-Qi Ma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(2):279-288
Various measures of entanglement have triggered considerable interest in the
relationship between entanglement measures and other
well-known quantities. As a demonstration, the dynamical
correlation of negativity and entropy is studied in two
coupled quartic oscillators for initial pure and mixed states that
are respectively taken to be the products and mixed density
matrices of coherent states and squeezed states on each
oscillator. The correlation with energy is also considered.
It is shown that for the initial pure states with a
small magnitude, two negativities are
positively correlated with the von Neumann entropy while they are anti-correlated with
the energy of each oscillator in the weak coupling regime. For mixed states
with a small magnitude the two negativities and the mutual entropy exhibit dominantly
positive correlation, whereas those three quantities are
dominantly anti-correlated with the sum of energies of two
oscillators in the case of weak interactions. Such correlation behaviors in the mixed
state with small magnitudes are most striking at the same step in
maximal and minimal values and in oscillation. The differences in
entropies and negativities between coherent states and squeezed
states are discussed. These are useful for quantum
entanglement and quantum information processing. 相似文献