Effect of boundaries on vacuum field fluctuations and radiation-mediated interactions between atoms

F Armata,R Incardone,S Butera,S Spagnolo,L Rizzuto,V Notararigo,R Passante,G Fiscelli,R Palacino

doi:10.1088/1742-6596/880/1/012064

Abstract

In this paper we discuss and review several aspects of the effect of boundary conditions and structured environments on dispersion and resonance interactions involving atoms or molecules, as well as on vacuum field fluctuations. We first consider the case of a perfect mirror, which is free to move around an equilibrium position and whose mechanical degrees of freedom are treated quantum mechanically. We investigate how the quantum fluctuations of the mirror’s position affect vacuum field fluctuations for both a one-dimensional scalar and electromagnetic field, showing that the effect is particularly significant in the proximity of the moving mirror. This result can be also relevant for possible gravitational effects, since the field energy density couples to gravity. We stress that this interaction-induced modification of the vacuum field fluctuations can be probed through the Casimir-Polder interaction with a polarizable body, thus allowing to detect the effect of the mirror’s quantum position fluctuations. We then consider the effect of an environment such as an isotropic photonic crystal or a metallic waveguide, on the resonance interaction between two entangled identical atoms, one excited and the other in the ground state. We discuss the strong dependence of the resonance interaction with the relative position of the atomic transition frequency with the gap of the photonic crystal in the former case, and with the cut-off frequency of waveguide in the latter.

Highlights

A peculiar aspect of the quantum theory is the presence of unavoidable quantum fluctuations of the fields, even in the ground state of the system [1]
We report some of our results on the resonance interaction between two two-level quantum emitters embedded in an isotropic three-dimensional photonic crystal, in two specific cases: (i) when their transition frequency is outside the gap and not far from its upper edge [19]; (ii) when it is inside the forbidden gap and in the proximity of its lower edge [24]
In the case (ii), that is when the atomic transition frequency ωa is inside the gap and in the proximity of its lower edge ωl, an explicit evaluation of the resonance interaction energy yields a scaling with the distance as r−2 in the far zone, rather than the r−1 behaviour obtained in the vacuum space

Summary

Introduction

A peculiar aspect of the quantum theory is the presence of unavoidable quantum fluctuations of the fields, even in the ground state of the system [1]. In this paper we shall discuss and review some aspects related to the role of fixed or moving boundaries on vacuum field energy densities and Casimir interactions, as well as the influence of a photonic bandgap environment or a metallic waveguide on the resonance (radiation-mediated) interaction between two entangled identical atoms, one excited and the other in the ground state.

Results

Conclusion