Harvesting Entanglement by non-identical detectors with different energy gaps

TL;DR

This paper investigates how non-identical detectors with different energy gaps can more effectively harvest entanglement from the vacuum state of a quantum field, revealing optimal conditions and advantages over identical detectors.

Contribution

It demonstrates that non-identical detectors can harvest more entanglement and at larger separations than identical detectors, identifying optimal energy gap differences for entanglement harvesting.

Findings

Non-identical detectors can extract more entanglement than identical ones.

An optimal energy gap difference maximizes harvested entanglement.

Energy gap differences extend the maximum separation for entanglement harvesting.

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.