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

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 orthogonal-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 orthogonal-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.

Entanglement harvesting in cosmic string spacetime

“…while in the case of the orthogonal-to-boundary alignment it becomes First, the presence of a cosmic string may either assist or inhibit entanglement harvesting, depending on the detectorto-string distance. For a small detector-to-string distance (l/σ ≪ 1), the presence of the cosmic string will assist entanglement harvesting in both parallel and orthogonal alignments, which is in sharp contrast to the inhibitory role played by the presence of a reflecting plane boundary in entanglement harvesting in the vicinity of the boundary [23,28]. However, for a sufficiently large detector-to-string distance, given a fixed interdetector separation d and a fixed deficit-angle parameter ν, the amount of harvested entanglement falls below the corresponding result in a flat spacetime without a cosmic string.…”

“…In addition, the dependence of concurrence on the detector-to-boundary distance in a flat spacetime with a reflecting plane boundary is also depicted in these plots for comparison. To facilitate this comparison, we refer to the results for the case with a reflecting boundary in JHEP06(2024)161 a flat spacetime, as detailed in references [23,28]. The transition probability of the detector, according to these studies, satisfies [see eq.…”

“…The phenomenon of entanglement harvesting has since been explored across various settings . Entanglement harvesting has been shown to be highly sensitive to several aspects of spacetime, including its topology [12,23,28] and curvature [11,[13][14][15][16], and those of the detectors, such as their superpositions of temporal order [21], intrinsic motion [18,20,23,24] and energy gaps [26][27][28]. It has been argued that this sensitivity to topology can serve as a tool to differentiate between locally flat spacetimes that are distinct only in their topological structures [12].…”

“…Recent studies have uncovered that the presence of a reflecting boundary in a flat spacetime, effectively rendering the spacetime topologically nontrivial, plays a notable role in the dynamics of entanglement harvesting. Specifically, it has been found to inhibit entanglement harvesting close to the boundary while facilitating it further away [23,28].…”