Quantum correlations of a two-qubit system and the Aubry-André chain in bosonic environments

He Wang, Liufang Xu, and Jin Wang
Phys. Rev. A 106, 052404 – Published 2 November 2022

Abstract

In this research we analyze two models using the tensor network algorithm. The quantum correlations of a two-qubit system are first studied in different bosonic reservoirs. Both equilibrium and nonequilibrium scenarios are discussed. Non-Markovian effects can improve the survival time of the quantum correlations significantly and weaken the decoherence effect. Non-Markovian dynamics with existing memory can lead to entanglement rebirth in specific scenarios instead of the eventual entanglement decay or death seen in memoryless Markovian cases. The system reaches a steady state quickest in sub-Ohmic reservoirs and shows the most apparent non-Markovian behavior in super-Ohmic reservoirs. The Markovian approximation used in this paper is superior to that in the Bloch-Redfield master equation. The entanglement dynamics behaves similarly under different approaches when the system-bath coupling is weak and the memory effect is significant when the system-bath coupling is strong. We study not only the impact of the environment on quantum correlations, but also how to protect quantum correlations. Starting from a state in which the two ends are maximally entangled, a one-dimensional Aubry-André chain model is also studied. We identify distinct phases by monitoring the imbalance dynamics. When the chain is closed, the imbalance dynamics behaves differently in various phases and so does the entanglement evolution between the chain's ends. When the first site couples to a bath, we find that the imbalance dynamics can still be an effective indicator to differentiate various phases in an early evolution stage since the imbalance dynamics is only remarkably affected at relatively high temperatures. The distribution of the eigenenergy of the system can account for it. The entanglement of the chain ends decays rapidly in all phases due to one of the ends being coupled to the bath directly. However, the entanglement of the chain ends will persist for a perceptible amount of time in the localization phase if the bath is coupled to the middle site of the chain. Our research shows that one can utilize the disordered environment as a buffer to protect quantum correlations.

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  • Received 30 March 2022
  • Revised 9 September 2022
  • Accepted 18 October 2022

DOI:https://doi.org/10.1103/PhysRevA.106.052404

©2022 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyStatistical Physics & Thermodynamics

Authors & Affiliations

He Wang

  • College of Physics, Jilin University, Changchun 130021, China and State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Changchun 130021, China

Liufang Xu*

  • College of Physics, Jilin University, Changchun 130021, China

Jin Wang

  • Department of Chemistry and Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3400, USA

  • *lfxuphy@jlu.edu.cn
  • jin.wang.1@stonybrook.edu

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Vol. 106, Iss. 5 — November 2022

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