Robustness of quantum correlation in quantum energy teleportation

TL;DR

This paper investigates the robustness of quantum correlations, measured by quantum discord, during quantum energy teleportation (QET) and finds that these correlations persist and relate to phase transitions, even when entanglement is broken.

Contribution

It introduces quantum discord as a measure of quantum correlation in QET, demonstrating its persistence and role as an order parameter across phase transitions in various models.

Findings

Quantum discord remains non-zero during QET, despite entanglement breaking.

Quantum discord acts as an order parameter for phase transitions.

Quantum correlations are robust across different phase structures in benchmark models.

Abstract

We present the evolution of quantum correlation in the quantum energy teleportation (QET) protocol using quantum discord, instead of the traditionally used entanglement entropy. In the QET protocol, where local observations and conditional operations are repeated, quantum correlations become nontrivial because of the statistical creation of mixed states. In this paper, we use quantum discord as a measure of quantum correlation in mixed states and investigate its relationship to teleported energy and phase transitions. During the process of Alice and Bob performing QET, one would expect that the entanglement between Alice and Bob is completely broken by Alice's measurement of the quantum state, and thus the quantum correlation disappears. However, contrary to this expectation, it is shown using quantum discord that the quantum correlation does not disappear during the entire process of QET. To demonstrate the robustness of the quantum correlation in QET at various phase structures, we perform the numerical analysis using several benchmark models including the Nambu-Jona-Lasino (NJL) model with both the chiral chemical potential and the chemical potential, which are useful to study the phase structures mimicking the chiral imbalance between left- and right- quarks coupled to the chirality density operator. In all cases we studied, the quantum discord behaved as an order parameter of the phase transition.