ENTANGLEMENT DYNAMICS MODULATED BY COUPLING STRENGTH IN CAVITY QED

2008 ◽  
Vol 06 (02) ◽  
pp. 341-346 ◽  
Author(s):  
ZHONG-XIAO MAN ◽  
SU FANG ◽  
YUN-JIE XIA
Keyword(s):  
Energy Transfer ◽  
Sudden Death ◽  
Cavity Qed ◽  
Entanglement Sudden Death ◽  
Entanglement Dynamics ◽  
Entanglement Evolution ◽  
Qubit System ◽  
Coupling Strengths ◽  
Entangled Atoms ◽  
Separate Cavities

We study the dynamics of entanglement for a four-qubit system in cavity QED. Two initially entangled atoms A and B are coupled respectively with spatially separate cavities a and b with coupling strengths gA and gB. We show that when gA ≠ gB, the entanglement will oscillate in the period of entanglement sudden death (ESD) for gA = gB, and the oscillation times are related to the ratios between gA and gB. Also, we show that the coupling strengths have the same effects on the entanglement evolution and energy transfer.

A STUDY ON THE SUDDEN DEATH AND SUDDEN BIRTH OF ENTANGLEMENT IN AN OPEN SYSTEM

2009 ◽  
Vol 07 (05) ◽  
pp. 949-957 ◽  
Author(s):  
YING-JIE ZHANG ◽  
YUN-JIE XIA
Keyword(s):  
Sudden Death ◽  
Open System ◽  
Entangled State ◽  
Entanglement Sudden Death ◽  
Entanglement Dynamics ◽  
Entanglement Evolution ◽  
Pure Case

In this paper, we consider the entanglement dynamics of two cavities interacting with independent reservoirs. When the cavity entanglement suddenly disappeared, the reservoir entanglement suddenly and necessarily appears. We study the effect of purity of initial entangled state of two cavities on the entanglement evolution, and acquire that the purity of initial entangled state of two cavities can control the apparition time of the entanglement sudden death and the entanglement sudden birth. Also, we find that the conditions on the apparition of the entanglement sudden death and the entanglement sudden birth can be generalized when the initial entangled state of cavities is not pure, which is a complement to the result in the paper [Phys. Rev. Lett.101 (2008) 080503] for the pure case.

Three-Atom Entanglement Sudden Death and Birth in Cavity QED with the Influence of the Stark Shift

2013 ◽  
Vol 662 ◽  
pp. 537-542 ◽  
Author(s):  
Kun Hua Wu ◽  
Qing Feng Huang ◽  
Xiao Qing Zhang
Keyword(s):  
Sudden Death ◽  
Quantum System ◽  
Cavity Qed ◽  
Stark Shift ◽  
The Other ◽  
Entanglement Sudden Death ◽  
Entanglement Dynamics

We investigate the entanglement dynamics in a quantum system consisting of three two-level atoms interacting with three spatially separated cavities with the influence of the Stark shift, and we can find that the entanglement sudden death (ESD) and birth (ESB) will be improved by adjusting the Stark parameters. When we choose the appropriate Stark parameters, the phenomena of ESD and ESB will be appeared, but, which will appear earlier than the other depends on the Stark-shift values.

scholarly journals TOPOLOGY OF ENTANGLEMENT EVOLUTION OF TWO QUBITS

2012 ◽  
Vol 26 (07) ◽  
pp. 1250054 ◽  
Author(s):  
DONG ZHOU ◽  
GIA-WEI CHERN ◽  
JIANJIA FEI ◽  
ROBERT JOYNT
Keyword(s):  
Sudden Death ◽  
Critical Points ◽  
Polarization Vector ◽  
Entanglement Sudden Death ◽  
Entanglement Evolution ◽  
Separable States ◽  
Qubit System ◽  
Asymptotic Point ◽  
Lower Dimensional

The dynamics of a two-qubit system is considered with the aim of a general categorization of the different ways in which entanglement can disappear in the course of the evolution, e.g., entanglement sudden death. The dynamics is described by the function n(t), where n is the 15-dimensional polarization vector. This representation is particularly useful because the components of n are direct physical observables, there is a meaningful notion of orthogonality, and the concurrence C can be computed for any point in the space. We analyze the topology of the space S of separable states (those having C = 0), and the often lower-dimensional linear dynamical subspace D that is characteristic of a specific physical model. This allows us to give a rigorous characterization of the four possible kinds of entanglement evolution. Which evolution is realized depends on the dimensionality of D and of D∩S, the position of the asymptotic point of the evolution, and whether or not the evolution is "distance-Markovian", a notion we define. We give several examples to illustrate the general principles, and to give a method to compute critical points. We construct a model that shows all four behaviors.

Entanglement sudden death via two-photon processes in cavity QED

2009 ◽  
Vol 42 (19) ◽  
pp. 195507 ◽  
Author(s):  
W B Cardoso ◽  
A T Avelar ◽  
B Baseia ◽  
N G de Almeida
Keyword(s):  
Sudden Death ◽  
Cavity Qed ◽  
Entanglement Sudden Death ◽  
Two Photon

ENTANGLEMENT DYNAMICS OF TWO QUBITS COUPLED TO SQUEEZED DISSIPATIVE ENVIRONMENTS

2010 ◽  
Vol 24 (26) ◽  
pp. 2635-2645
Author(s):  
CHUAN-JIA SHAN ◽  
TAO CHEN ◽  
JI-BING LIU ◽  
WEI-WEN CHENG ◽  
TANG-KUN LIU ◽  
...  
Keyword(s):  
Steady State ◽  
Sudden Death ◽  
Entangled States ◽  
Entanglement Sudden Death ◽  
Entanglement Dynamics ◽  
Initial Product ◽  
System Parameters ◽  
Initial States ◽  
Dissipative Environments ◽  
Degree Of Entanglement

By analytically solving the Lindblad form of the master equation, we investigate entanglement dynamics of two qubits coupled via the XY interaction, where each qubit is interacting with an independent reservoir with the squeezing parameters and squeezing angles. In the weak-squeezed reservoir, we show that the entanglement sudden death and entanglement sudden birth will happen for various entangled states. Some initial product states evolve into entangled ones, initially entangled states lose completely or partially their entanglement. The effects of varying the degree of entanglement of the initial states, the spin chain system parameters and different values of the degree of squeezing on the sudden death, revival and birth times are analyzed in detail. We also see that the steady state concurrence appears in the squeezed dissipative environments, which is affected by both the system parameters and the degree of squeezing.

scholarly journals Controlling entanglement sudden death and birth in cavity QED

2009 ◽  
Vol 282 (17) ◽  
pp. 3652-3655 ◽  
Author(s):  
Jian-Song Zhang ◽  
Jing-Bo Xu
Keyword(s):  
Sudden Death ◽  
Cavity Qed ◽  
Entanglement Sudden Death

Influence of the Stark Shift on Entanglement Sudden Death and Birth in Cavity QED

2011 ◽  
Vol 28 (1) ◽  
pp. 010301 ◽  
Author(s):  
Jian-Song Zhang ◽  
Ai-Xi Chen ◽  
Kun-Hua Wu
Keyword(s):  
Sudden Death ◽  
Cavity Qed ◽  
Stark Shift ◽  
Entanglement Sudden Death

scholarly journals Engineering decoherence for two-qubit systems interacting with a classical environment

2014 ◽  
Vol 12 (07n08) ◽  
pp. 1560003 ◽  
Author(s):  
Matteo A. C. Rossi ◽  
Claudia Benedetti ◽  
Matteo G. A. Paris
Keyword(s):  
Sudden Death ◽  
Initial Level ◽  
Bell States ◽  
Entanglement Sudden Death ◽  
Fractional Gaussian Noise ◽  
Gaussian Stochastic Process ◽  
Fractional Noise ◽  
Death Time ◽  
Qubit System ◽  
Increasing Function

We address the dynamics of a two-qubit system interacting with a classical dephasing environment driven by a Gaussian stochastic process. Upon introducing the concept of entanglement-preserving time, we compare the degrading effects of different environments, e.g. those described by Ornstein–Uhlenbeck (OU) or fractional noise. In particular, we consider pure Bell states and mixtures of Bell states and study the typical values of the entanglement-preserving time for both independent and common environments. We found that engineering environments towards fractional Gaussian noise is useful to preserve entanglement as well as to improve its robustness against noise. We also address entanglement sudden death by studying the sudden-death time as a function of the initial negativity. We found that: (i) the sudden-death time is bounded from below by an increasing function of the initial negativity, (ii) the sudden-death time depends only slightly on the process used to describe the environment and exhibits typicality. Overall, our results show that engineering the environment has only a slight influence over the entanglement sudden-death time, while it represents a valuable resource to increase the entanglement-preserving time, i.e. to maintain entanglement closer to the initial level for a longer interaction time.

ENTANGLEMENT TRANSFER IN A MULTIPARTITE CAVITY QED OPEN SYSTEM

2011 ◽  
Vol 09 (supp01) ◽  
pp. 83-92 ◽  
Author(s):  
MATTEO BINA ◽  
FEDERICO CASAGRANDE ◽  
ALFREDO LULLI ◽  
MARCO G. GENONI ◽  
MATTEO G. A. PARIS
Keyword(s):  
Sudden Death ◽  
Cavity Qed ◽  
Optical Cavity ◽  
Single Mode ◽  
Entanglement Sudden Death ◽  
Dissipative Effects ◽  
State Transfer ◽  
Cavity Modes ◽  
Entanglement Transfer ◽  
Multi Mode

We describe the dynamics of tripartite state mapping and entanglement transfer from qubit-like radiation states to two-level atoms via optical cavity modes. When the entangled radiation is carried to the cavities by single-mode fibers, optimal pure and mixed state transfer is predicted for perfect mirror transmittance, and entanglement sudden death (and birth) is demonstrated for Werner input states. The general case of multi-mode fiber coupling is also discussed. The dynamics is finally investigated under various dissipative effects.

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