Finite-temperature entanglement and coherence in asymmetric bosonic Josephson junctions

TL;DR

This paper studies how finite temperature and asymmetry influence entanglement and coherence in a bosonic Josephson junction, providing numerical and analytical insights into their dependence on system parameters.

Contribution

It introduces an effective temperature approach for the strong tunneling regime, enhancing understanding of thermal effects in asymmetric bosonic Josephson systems.

Findings

Finite temperature reduces entanglement and coherence.

Asymmetry significantly affects quantum properties.

Analytical expressions are derived for the strong tunneling regime.

Abstract

We investigate the finite-temperature properties of a bosonic Josephson junction composed of N interacting atoms confined by a quasi-one-dimensional asymmetric double-well potential, modeled by the two-site Bose-Hubbard Hamiltonian. We compute numerically the spectral decomposition of the statistical ensemble of states, the thermodynamic and entanglement entropies, the population imbalance, the quantum Fisher information, and the coherence visibility. We analyze their dependence on the system parameters, showing in particular how finite temperature and on-site energy asymmetry affect the entanglement and coherence properties of the system. Moreover, starting from a quantum phase model which accurately describes the system over a wide range of interactions, we develop a reliable description of the strong tunneling regime, where thermal averages may be computed analytically using a modified Boltzmann weight involving an effective temperature. We discuss the possibility of applying this effective description to other models in suitable regimes.