Van der Waals and resonance interactions between accelerated atoms in vacuum and the Unruh effect

S Spagnolo,J Marino,W Zhou,L Rizzuto,R Passante,M Lattuca,A Noto

doi:10.1088/1742-6596/880/1/012042

Abstract

We discuss different physical effects related to the uniform acceleration of atoms in vacuum, in the framework of quantum electrodynamics. We first investigate the van der Waals/Casimir-Polder dispersion and resonance interactions between two uniformly accelerated atoms in vacuum. We show that the atomic acceleration significantly affects the van der Waals force, yielding a different scaling of the interaction with the interatomic distance and an explicit time dependence of the interaction energy. We argue how these results could allow for an indirect detection of the Unruh effect through dispersion interactions between atoms. We then consider the resonance interaction between two accelerated atoms, prepared in a correlated Bell-type state, and interacting with the electromagnetic field in the vacuum state, separating vacuum fluctuations and radiation reaction contributions, both in the free-space and in the presence of a perfectly reflecting plate. We show that nonthermal effects of acceleration manifest in the resonance interaction, yielding a change of the distance dependence of the resonance interaction energy. This suggests that the equivalence between temperature and acceleration does not apply to all radiative properties of accelerated atoms. To further explore this aspect, we evaluate the resonance interaction between two atoms in non inertial motion in the coaccelerated (Rindler) frame and show that in this case the assumption of an Unruh temperature for the field is not required for a complete equivalence of locally inertial and coaccelerated points of views.

Highlights

A remarkable consequence of quantum field theory in accelerated frames is that the concept of vacuum is observer-dependent [1, 2, 3]
We explore the effect of atomic acceleration on both van der Waals/CasimirPolder and resonance interactions between two atoms moving with the same uniform acceleration in the vacuum, in the free space or in the presence of a reflecting plane boundary
We show that the atomic acceleration significantly affects the van der Waals interaction between the two accelerated atoms, resulting in a different scaling of the interaction with the distance compared to inertial atoms and in an explicit time dependence of the interaction

Summary

Introduction

A remarkable consequence of quantum field theory in accelerated frames is that the concept of vacuum is observer-dependent [1, 2, 3]. A different related question recently addressed in the literature, is whether the effects of a relativistic acceleration are strictly equivalent to a thermal field and what is the physical meaning of this equivalence [7, 12] It has been recently discussed, for example, that nonthermal features associated with a uniform acceleration appear in the radiative properties of single accelerated atoms [13, 14], as well as in the van der Waals/Casimir-Polder interaction between atoms in non inertial motion [15], or in the entanglement generation between two accelerating atoms [16, 17]. This is a quite relevant feature of our result (2), since it suggests that modifications to the interaction energy between the two atoms could be observed for reasonable values of the acceleration, provided that sufficiently long times are considered [23] All this could be of relevance for a possible indirect detection of the Unruh effect through the van der Waals force between two accelerated atoms

Resonance interaction between two accelerated atoms in vacuum

Conclusions