Robustness of quantum correlations against decoherence

S. Bhuvaneswari, R. Muthuganesan, R. Radha

A.‐B. A. Mohamed, Hichem Eleuch

We investigate the dynamics of quantum correlations [including skew information correlations beyond entanglement] of two isolated Su(2)-systems that are initially in a maximum Bell state or in a separable state. Each Su(2)-system is interacting with two-mode Su(1,1) coherent states. The time evolution of the density matrix of the two Su(2)-systems with the effect of intrinsic decoherence is analytically explored. The robustness of the initial quantum correlations for several initial coherence intensities, detunings, and intrinsic decoherences, is investigated. The robustness analysis of various correlation functions is based on the concurrence and quantum skew information. It is shown that the phenomena of sudden death and birth entanglement, and the sudden changes of local quantum uncertainty can be controlled. The correlations of the skew information present good robustness against the intrinsic decoherence and the detuning.

Chunfang Sun, Zhihua Chen, Gangcheng Wang +3 more

S. V. Mousavi

A.‐B. A. Mohamed, M. Sebaweh Abdalla, A.‐S. F. Obada

Two two-level systems generated by su(2) algebra are initially prepared in a maximum nonsymmetric Bell state and having no mutual interaction. Each su(2)-system spatially interacts with two-mode cavity field in the nondegenerate parametric amplifier type cast through operators governed by su(1, 1) Lie algebra. An analytical description for the time evolution of the final state of the total system with the effect of intrinsic decoherence is found. Therefore, the robustness of the quantum correlations between the two su(2)-system is investigated by means of geometric quantum discord, measurement-induced nonlocality and negativity. We analyze in some detail the influence of initial coherence intensities, detuning and phase decoherence parameters on the steady-state correlation. We find that the steady-state correlations can be generated and enhanced by controlling the parameters of: the initial coherence intensities, the Bargmman index and the detuning. It is shown that the phenomenon of sudden death and re-birth of entanglement, and the sudden changes of the geometric quantum correlation can be controlled by these parameters. We find that the robustness of the quantum correlation can be greatly enhanced by the Bargmman index and the resonance detuning. Negativity is the measure most susceptible to phase decoherence, while geometric quantum discord and measurement-induced nonlocality are the more robust measures.

AI Jian-feng, Jian-Song Zhang, Aixi Chen

We investigate the transfer of bipartite (measured by cocurrence) and multipartite (measured by global discord) quantum correlations though spin chains under phase decoherence. The influence of phase decoherence and anisotropy parameter upon quantum correlations transfer is investigated. On the one hand, in the case of no phase decoherence, there is no steady state quantum correlations between spins. On the other hand, if the phase decoherence is larger than zero, the bipartite quantum correlations can be transferred through a Heisenberg XXX chain for a long time and there is steady state bipartite entanglement. For a Heisenberg XX chain, bipartite entanglement between two spins is destroyed completely after a long time. Multipartite quantum correlations of all spins are more robust than bipartite quantum correlations. Thus, one can store multipartite quantum correlations in spin chains for a long time under phase decoherence.