Harvesting correlations from vacuum quantum fields in the presence of a reflecting boundary

TL;DR

This paper investigates how a reflecting boundary affects the ability of two static detectors to harvest quantum correlations, such as mutual information and entanglement, from vacuum scalar fields, revealing boundary-dependent effects and optimal detector configurations.

Contribution

It provides a detailed analysis of correlations harvesting near a reflecting boundary, highlighting boundary effects, optimal detector parameters, and differences between detector alignments.

Findings

Boundary inhibits mutual information harvesting compared to free space.

Boundary inhibits entanglement harvesting near the boundary but can assist it farther away.

Vertical alignment yields more mutual information; proximity to boundary affects entanglement harvesting.

Abstract

We explore correlations harvesting by two static detectors locally interacting with vacuum massless scalar fields in the presence of an infinite perfectly reflecting boundary. We study the phenomena of mutual information harvesting and entanglement harvesting for two detector-boundary alignments, i.e., parallel-to-boundary and vertical-to-boundary alignments. Our results show that the presence of the boundary generally inhibits mutual information harvesting relative to that in flat spacetime without any boundaries. In contrast, the boundary may play a doubled-edged role in entanglement harvesting, i.e., inhibiting entanglement harvesting in the near zone of the boundary while assisting it in the far zone of the boundary. Moreover, there exists an optimal detector energy gap difference between two nonidentical detectors that makes such detectors advantageous in correlations harvesting as long as the interdetector separation is large enough. The value of the optimal detector energy gap difference depends on both the interdetector separation and the detector-to-boundary distance. A comparison of the correlations harvesting in two different alignments shows that although correlations harvesting share qualitatively the same properties, they also display quantitative differences in that the detectors in vertical-to-boundary alignment always harvest comparatively more mutual information than the parallel-to-boundary ones, while they harvest comparatively more entanglement only near the boundary.