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1.
We investigate the entanglement dynamics and decoherence of a three-qubit system under a quantum spin environment at a finite temperature in the thermodynamics limit. For the case under study, we find the evolution of pairwise entanglement depends not only on the initial states but also on the parameters related to the system and the spin environment. In addition, an undesirable entanglement sudden death occurs in the process of entanglement evolution, and this effect can be controlled by the coupling constant between two qubits, external magnetic field, and the interaction between the system and the environment.  相似文献   

2.
The dynamics of entanglement between three-level atoms coupled to the common vacuum is investigated. We show that the collective effects such as collective damping, dipole-dipole interaction and the cross coupling between orthogonal dipoles, play a crucial role in the process of creation of entanglement. In particular, the additional cross coupling enhances the production of entanglement. For the specific initial states we find that the effect of delayed sudden birth of entanglement, recently invented by Ficek and Tana? [Ficek, R. Tana?, Phys. Rev. A 77 (2008) 054301] in the case of two-level atoms, can also be observed in the system. When the initial state is entangled, the process of spontaneous emission causes destruction of correlations and its disentanglement. We show that the robustness of initial entanglement against the noise can be changed by local operations performed on the state.  相似文献   

3.
庞朝阳  李玉良 《中国物理快报》2006,23(12):3145-3147
We investigate the dynamics of genuine three-qubit entanglement in the Ising model of three spins. A scheme is presented for generating the genuine three-qubit entanglement by the nearest-neighbour couplings. The effect of magnetic fields on the dynamics of genuine three-qubit entanglement is also discussed.  相似文献   

4.
We investigate the entanglement dynamics of a quantum system consisting of two-level atoms interacting with vacuum or thermal fields with classical driving fields. We find that the entanglement of the system can be improved by adjusting the classical driving field. The influence of the classical field and the purity of the initial state on the entanglement sudden death is also studied. It is shown that the time of entanglement sudden death can be controlled by the classical driving fields. Particularly, the entanglement sudden death phenomenon will disappear if the classical driving fields are strong enough.  相似文献   

5.
We study the dynamics of various branched spin chain systems. In such systems entanglement can be generated and distributed, providing an essential resource for teleportation or distributed quantum processing. We show in detail how simple operations can be employed at chosen times to change the subsequent dynamics of the branched spin chains, rendering the distributed entanglement more accessible.  相似文献   

6.
The effects of dissipative dynamics on the magnitude of entanglement generated In atom-photon interactions inside cavities is studied. We present some concrete examples of environment Induced entanglement in alom-photon interactions. We consider various dissipative atom-cavity systems and show that their collective dynamics can be used to maximize entanglement for intermediate values of the cavity leakage parameter κ. We first consider the interaction of a single two-level atom with one of two coupled microwave cavities and show analytically that the atom-cavity entanglement increases with cavity leakage. We next consider a system of two atoms passing successively through a cavity and derive the expression for the maximum value of in terms of the Rabi angle gt, for which the two-atom entanglement can be Increased. Finally, numerical investigation of micromaser dynamics also reveals the increase of two-atom entanglement with stronger cavity-environment coupling for experimentally attainable values of the micromaser parameters.  相似文献   

7.
We investigate the entanglement dynamics and decoherence of a multipartite system under an environment which can exhibit a quantum phase transition. Our result implies that the entanglement evolution depends not only on the size of the system and the quantum states of concern but also on the environment. In the sense of the linear entropy to measure decoherence induced by the environment, the decoherence-free subspaces have been identified for our model.  相似文献   

8.
We propose a scheme to enhance the entanglement of a dissipative system, and the enhancement is happened during certain intervals of the evolution time. Our method is obtained by introducing one impurity into a Heisenberg XY chain and then solving the Lindblad form of the master equation with different initial states. The dynamics of entanglement reveal that one can significantly enhance the entanglement. This result will be helpful for the generation and transportation of entanglement in real solid-state systems.  相似文献   

9.
Quantum mechanics has many counter-intuitive consequences which contradict our intuition which is based on classical physics. Here we discuss a special aspect of quantum mechanics, namely the possibility of entanglement between two or more particles. We will establish the basic properties of entanglement using quantum state teleportation. These principles will then allow us to formulate quantitative measures of entanglement. Finally we will show that the same general principles can also be used to prove seemingly difficult questions regarding entanglement dynamics very easily. This will be used to motivate the hope that we can construct a thermodynamics of entanglement.  相似文献   

10.
We investigate the entanglement dynamics and purity of a two-level atom, which is additionally driven by a classical field, interacting with a coherent field in a dissipative environment. It is shown that the amount of entanglement and the purity of the system can be improved by controlling the classical field.  相似文献   

11.
We investigate the entanglement dynamics and Bell violation of three-qubit quantum states under an environment consisting of an XY spin chain with Dzyaloshinski–Moriya (DM) interaction. From the results, we find that the entanglement dynamics depends not only on the DM interaction, the magnetic field, and the anisotropy parameter but also on the number of the freedom degrees of the environment. The decoherence-free subspaces of our model have been identified and the Bell violation of quantum states is also discussed.  相似文献   

12.
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   

13.
In this paper, we use the Weisskopf-Wigner theory to study the entanglement in the state of the free-space radiation field produced from vacuum due to atomic decay. We show how bipartite entanglement is shared between different partitions of the radiation modes. We investigate the role played by the size of the partitions and their detuning with the decaying atom. The dynamics of the atom-field entanglement during the atomic decay is also briefly discussed. From this dynamics, we assert that such entanglement is the physical quantity that fix the statistical atomic decay time.  相似文献   

14.
By analytically solving the master equation, we examine entanglement dynamics of the two-qubit spin system coupled via the XY interaction and in the presence of population relaxation. We found that the entanglement dynamical behaviors are very sensitive to different initialized states. Particularly, for initial states ?=(|01〉〈01|+|10〉〈10|)/2 and ?=(|00〉〈00|+|11〉〈11|)/2, a combination of the XY coupling with the population relaxation can even be used to enhance the entanglement. Moreover, we show that among different initially separable states, ?=|01〉〈01| and ?=|10〉〈10| are more robust in generating pairwise entanglement.  相似文献   

15.
The time evolution of entanglement and coherence of two-qutrit states under an XY quantum environment which can exhibit a quantum phase transition has been analyzed. From our results, we find that the quantum phase transition can enhance the entanglement decay and coherence loss when the system is weakly coupled to the environment. Furthermore, the effect of the anisotropy parameter and the size of the environment on entanglement dynamics and coherence has also been discussed.  相似文献   

16.
The entanglement dynamics in a system of the interaction of an atom with a single-mode thermal field in the presence of noise is studied by the Jaynes-Cummings model. Two-state random phase telegraph noise is considered as the noise in the interaction and an exact solution to the model under this noise is obtained by the Burshtein equation. Although the Burshtein equation is applicable for laser-atom interactions, it is shown that it can be applied to atom-thermal field system as a special case. The solution is used to investigate the entanglement dynamics of the atom-field interaction by calculating a lower bound on concurrence. It is found that the entanglement is a non monotonic function of the intensity of the noise. The degree of the entanglement decreases to a minimum value for an optimal intensity of the noise and then increases for a sufficiently large intensity. Moreover, intense noise may generate stronger entanglement compared with the absence of noise.  相似文献   

17.
We investigate the quantum coherence and quantum entanglement dynamics of a classical driven single atom coupled to a single-mode cavity. It is shown that the transformation between the atomic coherence and the atom-field entanglement exists, and can be improved by adjusting the classical driving field. The joint evolution of two identical single-body systems is also studied. The results show the quantum coherence transfers among composite subsystems, and the coherence conservation of composite subsystems is obtained. Moreover, the classical driving field can be used to suppress the decay of the coherence and entanglement, owing to considering the leaky cavity. The non-Markovian dynamics of the system is also discussed finally.  相似文献   

18.
By means of composite quantum collision models, we study the entanglement dynamics of a bipartite system, i.e.,two qubits S1 and S2 interacting directly with an intermediate auxiliary qubit SA, while SAis in turn coupled to a thermal reservoir. We are concerned with how the intracollisions of the reservoir qubits influence the entanglement dynamics. We show that even if the system is initially in the separated state, their entanglement can be generated due to the interaction between the qubits. In the long-time limit, the steady-state entanglement can be generated depending on the initial state of S1 and S2 and the environment temperature. We also study the dynamics of tripartite entanglement of the three qubits S1,S2, and SAwhen they are initially prepared in the GHZ state and separated state, respectively. For the GHZ initial state,the tripartite entanglement can be maintained for a long time when the collision strength between the environment qubits is sufficiently large.  相似文献   

19.
Z.Y. Xu  M. Feng 《Physics letters. A》2009,373(22):1906-1910
We investigate the entanglement dynamics of two initially entangled qubits interacting independently with two uncorrelated reservoirs beyond the Markovian approximation. Quite different from the Markovian reservoirs [C.E. López, et al., Phys. Rev. Lett. 101 (2008) 080503], we find that entanglement sudden birth (ESB) of the two reservoirs occurs without certain symmetry with respect to the entanglement sudden death (ESD) of the two qubits. A phenomenological interpretation of entanglement revival is also given.  相似文献   

20.
We evaluate the dynamics of two-qubit quantum discord(QD) under the classical phase noise. We compare the dynamics of QD with that of entanglement as measured with concurrence. The influence of mixture degree on the dynamics is also discussed. The results show that there is no simple relation between the quantum correlation and entanglement as seen that QD may be smaller or larger than entanglement, and QD is more robust than the entanglement.  相似文献   

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