One-way deficit and quantum phase transitions in $XX$ Model

TL;DR

This paper investigates how the one-way quantum deficit can serve as an indicator of quantum phase transitions in the XX model, linking quantum thermodynamics with critical phenomena.

Contribution

It demonstrates that the one-way deficit signals the quantum phase transition in the XX model, providing a new thermodynamic perspective on quantum criticality.

Findings

One-way deficit becomes nonzero after the critical point.

It characterizes the quantum phase transition in the XX model.

The study links quantum thermodynamics with quantum phase transitions.

Abstract

Quantum correlations including entanglement and quantum discord has drawn much attention in characterizing quantum phase transitions. Quantum deficit originates in questions regarding work extraction from quantum systems coupled to a heat bath [Phys. Rev. Lett. 89, 180402 (2002)]. It links quantum thermodynamics with quantum correlations and provides a new standpoint for understanding quantum non-locality. In this paper, we evaluate the one-way deficit of two adjacent spins in the bulk for the XX model. In the thermodynamic limit, the XX model undergoes a first order transition from fully polarized to a critical phase with quasi-long-range order with decrease of quantum parameter. We find that the one-way deficit becomes nonzero after the critical point. Therefore, the one-way deficit characterizes the quantum phase transition in the XX model.