Entanglement harvesting from multiple massless scalar fields and divergences in Unruh-DeWitt detector models

TL;DR

This paper investigates how Unruh-DeWitt detectors harvest entanglement from various scalar fields, revealing that the dynamics are largely insensitive to field type and identifying persistent divergences in quadratic couplings.

Contribution

It demonstrates that detector dynamics depend on the Wightman function of a real scalar field regardless of field type and discusses regularization methods for divergences in quadratic couplings.

Findings

Entanglement harvesting is insensitive to scalar field type or charge.

Detector dynamics depend on the Wightman function of a real scalar field.

Persistent divergences occur in quadratic and bi-linear couplings, requiring regularization.

Abstract

We analyze scenarios in which pairs of Unruh-DeWitt-like detectors interact with scalar field(s) with bi-linear and quadratic coupling. For all cases -- real scalar fields, charged scalar fields, and even for couplings mixing two different scalar fields -- we find that the detectors' dynamics depends on the Wightman function of a real scalar field with the same functional form up to a constant multiple. Consequently, entanglement harvesting exhibits low sensitivity to either the kind of scalar field or their charged nature. Furthermore, we show on general grounds that pairs of Unruh-DeWitt-like detectors exhibit persistent divergences when they interact with scalar field(s) with a quadratic or bi-linear coupling and discuss possible avenues to improve the models through the regularization of such divergences.