Entanglement preservation in tripartite quantum systems under dephasing dynamics

¹ Department of Computer Science and Engineering, NYU Shanghai - 567 West Yangsi Road, Pudong, Shanghai 200126, China
² Department of Mathematics, Techno Main Salt Lake (Engg. Colg.), Techno India Group - EM 4/1, Sector V, Salt Lake, Kolkata 700091, India
³ Department of Physics, University of Wisconsin-Madison - Madison, WI 53706, USA
⁴ Centre for Quantum Science and Technology, Chennai Institute of Technology - Chennai 600069, India

Received: 21 October 2023
Accepted: 15 April 2024

Abstract

Protecting entanglement from decoherence is a critical aspect of quantum information processsing. For many-body quantum systems evolving under decoherence, estimating multipartite entanglement is challenging. This challenge can be met up by considering a distance-based measure such as relative entropy of entanglement which decisively measures entanglement in both pure as well as mixed states. In this work, we investigate the tripartite entanglement dynamics of pure and mixed states in the presence of a structured dephasing environment at finite temperature. We show that the robustness of the quantum system to decoherence is dependent on the distribution of entanglement and its relation to different configurations of the bath. If the bath is structured individually such that each qubit has its own environment, the system has different dynamics compared to when the bath is common to all the three qubits. From the results we conjecture that there is a connection between the distribution of entanglement among the qubits and the distribution of bath degrees of freedom, and the interplay of these two distributions determines the decay rate of the entanglement dynamics. The sustainability of tripartite entanglement is shown to be enhanced significantly in the presence of reservoir memory.