Transition processes of a static multilevel atom in the cosmic string spacetime with a conducting plane boundary

Huabing Cai,Zhongzhou Ren

doi:10.1038/s41598-018-30260-9

Abstract

We investigate the transition processes of a static multilevel atom in interaction with a fluctuating vacuum quantum electromagnetic field in the cosmic string spacetime in the presence of an infinite, perfectly conducting plane. Using the formalism proposed by DDC, we find that the presence of the boundary modifies both vacuum fluctuations and radiation reaction contributions to the atomic spontaneous emission rate. Our results indicate that the total decay rate and the boundary-induced contribution both depend upon the atom-string distance, the atom-plate separation, the extent of the polar angle deficit induced by the string, and the atomic polarization direction. By adjusting these parameters, the atomic decay rate can be either enhanced or weakened significantly by the boundary. Moreover, the presence of the boundary can distinguish certain polarization directions that bring about the same decay rate in the case of a free cosmic string spacetime. Theoretically, our work suggests a more flexible means to adjust and control the radiative processes of atoms.

Highlights

Spontaneous emission process of atoms is one of the prominent quantum phenomena and it involves the interaction of atoms with the surrounding radiation field
Using the formalism proposed by Dupont-Roc and Cohen-Tannoudji (DDC), we separate the contributions of vacuum fluctuations and radiation reaction to the atomic transition rates and explore how they rely on the boundary
By employing the previously developed formalism, we investigate in detail the atomic radiative properties for the case when the surrounding field is confined by a perfectly conducting plane boundary

Summary

Introduction

Spontaneous emission process of atoms is one of the prominent quantum phenomena and it involves the interaction of atoms with the surrounding radiation field. As discussed by Dalibard, Dupont-Roc and Cohen-Tannoudji (DDC), separating the field operator into the “free” part, i.e. the free field operator in the absence of the atom-field coupling, and the “source” part only caused by the atom-field coupling and choosing a symmetric atom-field operator ordering, vacuum fluctuations (“free” field) and radiation reaction (“source” field) contributions can be identified as both contributions are Hermitian and have independent physical meanings8,9 Within such a formalism, the stability of an inertial atom in the ground state in the Minkowski spacetime can be maintained by the interplay between the two contributions. In a more realistic situation, the radiative processes of a static multilevel atom or two two-level entangled atoms in interaction with a quantum electromagnetic field were investigated in the presence of a cosmic string Their results indicate that the atomic transition rates are crucially dependent on the atomic polarizability with respect to the string, in addition to the distance of the atom with the string.

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Results

Conclusion