Thermal amplification of field-correlation harvesting

TL;DR

This paper investigates how increasing the temperature of a quantum field can enhance the harvesting of classical and quantum correlations, especially mutual information and discord, using exact solutions in a cavity setting.

Contribution

It introduces a non-perturbative, exact approach to analyze correlation harvesting from a thermal field and reveals thermal amplification of discord and mutual information, contrary to entanglement decay.

Findings

Entanglement decreases with temperature

Mutual information and discord increase with temperature

Thermal amplification enables new quantum information protocols

Abstract

We study the harvesting of quantum and classical correlations from a hot scalar field in a periodic cavity by a pair of spatially separated oscillator-detectors. Specifically, we utilize non-perturbative and exact (non-numerical) techniques to solve for the evolution of the detectors-field system and then we examine how the entanglement, Gaussian quantum discord, and mutual information obtained by the detectors change with the temperature of the field. While (as expected) the harvested entanglement rapidly decays to zero as temperature is increased, we find remarkably that both the mutual information and the discord can actually be increased by multiple orders of magnitude via increasing the temperature. We go on to explain this phenomenon by taking advantage of the translational invariance of the field and use this to make accurate predictions of the behavior of thermal amplification; by this we also introduce a new perspective on field-correlation harvesting that we feel is worthy of consideration in its own right. The thermal amplification of discord harvesting represents an exciting prospect for discord-based quantum computation, including its use in entanglement activation.