Harvesting Entanglement by non-identical detectors with different energy gaps

Abstract

It has been shown that the vacuum state of a free quantum field is entangled and such vacuum entanglement can be harvested by a pair of initially uncorrelated detectors interacting locally with the vacuum field for a finite time. In this paper, we examine the entanglement harvesting phenomenon of two non-identical inertial detectors with different energy gaps locally interacting with massless scalar fields via a Gaussian switching function. We focus on how entanglement harvesting depends on the energy gap difference from two perspectives: the amount of entanglement harvested and the harvesting-achievable separation between the two detectors. In the sense of the amount of entanglement, we find that as long as the inter-detector separation is not too small with respect to the interaction duration parameter, two non-identical detectors could extract more entanglement from the vacuum state than the identical detectors. There exists an optimal value of the energy gap difference when the inter-detector separation is sufficiently large that renders the harvested entanglement to peak. Regarding the harvesting-achievable separation, we further find that the presence of an energy gap difference generally enlarges the harvesting-achievable separation range. Our results suggest that the non-identical detectors may be advantageous to extracting entanglement from vacuum in certain circumstances as compared to identical detectors.

Entanglement harvesting in cosmic string spacetime

“…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].…”

Entanglement harvesting of three Unruh-DeWitt detectors

“…The extracted entanglement can be further distilled into Bell pairs [26], indicating that in principle the vacuum is a resource for quantum information tasks. A considerable amount of research on this phenomenon has since been carried out [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], and the process has come to be known as entanglement harvesting [43,45]. In general it depends on the properties and states of motion of the detectors, and has been investigated for both spacelike and non-spacelike detector separations [46][47][48].…”

Entanglement Harvesting of Inertially Moving Unruh-DeWitt Detectors in Minkowski Spacetime

“…For simplicity the detectors are generally taken to be identical. However it was recently shown [31] that a differential energy gap between the detectors can, under the right circumstances, both extend the harvesting-achievable separation between the detectors and extract more entanglement from the vacuum state than is possible if the detector gaps are identical.…”