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arXiv 1205.3133quant-ph
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退相干下多体量子关联的动力学

Dynamics of multipartite quantum correlations under decoherence

M. Ramzan

摘要:

与其他相关测量相比,量子不和谐是量化经典和非经典相关性的最佳资源。量子不和谐的几何度量是量子相关性的另一种度量。最近,徐建伟介绍了多体态的几何量子不和谐[arxiv:quant/ph.1205.0330]。受最近研究[Ann.Phys.327(2012)851]的启发,我研究了不同多体态在外部环境影响下的全局量子不和谐(QD)和几何量子不和谐(GQD)。在惯性和非惯性条件下,分别考虑了Werner-GHZ型三量子比特态和六量子比特态。研究了量子点和广义量子点在振幅阻尼、相位阻尼、去极化和翻转通道下的动力学行为。可以看出,在三量子比特GHZ态的情况下,当p>0.75时,量子不和谐消失;在六量子比特GHZ态的情况下,当p>0.5时,量子不和谐消失。这意味着,多体态是更脆弱的消相干的N值越高。令人惊讶的是,不和谐的快速突然死亡发生在相位翻转通道的情况下。然而,对于位翻转通道,六量子位状态不会发生突然死亡。另一方面,与振幅阻尼通道相比,去极化通道对量子点和广义量子点的影响更大。这意味着去极化通道对多体态的不谐和具有最大的破坏性影响。从加速观测者的角度看,环境对量子点和广义量子点的影响要比非惯性系的加速度的影响大得多。由于Unruh效应,QD和GQD的降解发生。此外,当多部系统暴露于环境中时,QD比GQD表现出更强的鲁棒性。

英文摘要:

Quantum discord is an optimal resource for the quantification of classical and non-classical correlations as compared to other related measures. Geometric measure of quantum discord is another measure of quantum correlations. Recently, the geometric quantum discord for multipartite states has been introduced by Jianwei Xu [arxiv:quant/ph.1205.0330]. Motivated from the recent study [Ann. Phys. 327 (2012) 851] for the bipartite systems, I have investigated global quantum discord (QD) and geometric quantum discord (GQD) under the influence of external environments for different multipartite states. Werner-GHZ type three-qubit and six-qubit states are considered in inertial and non-inertial settings. The dynamics of QD and GQD is investigated under amplitude damping, phase damping, depolarizing and flipping channels. It is seen that the quantum discord vanishes for p>0.75 in case of three-qubit GHZ states and for p>0.5 for six qubit GHZ states. This implies that multipartite states are more fragile to decoherence for higher values of N. Surprisingly, a rapid sudden death of discord occurs in case of phase flip channel. However, for bit flip channel, no sudden death happens for the six-qubit states. On the other hand, depolarizing channel heavily influences the QD and GQD as compared to the amplitude damping channel. It means that the depolarizing channel has the most destructive influence on the discords for multipartite states. From the perspective of accelerated observers, it is seen that effect of environment on QD and GQD is much stronger than that of the acceleration of non-inertial frames. The degradation of QD and GQD happens due to Unruh effect. Furthermore, QD exhibits more robustness than GQD when the multipartite systems are exposed to environment.

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