Spontaneous excitation of an accelerated atom in a spacetime with a reflecting plane boundary

TL;DR

This paper investigates how a reflecting boundary influences the spontaneous excitation and radiation of an accelerated atom, revealing boundary-induced oscillations and vacuum fluctuation effects related to the Unruh phenomenon.

Contribution

It provides a detailed analysis of boundary effects on atomic radiation and acceleration-induced excitations, linking them to observable phenomena in flat spacetime.

Findings

Boundary causes oscillations in atomic radiation rates near the boundary.

Accelerated atoms can be excited from the ground state due to boundary and acceleration effects.

The results suggest possible experimental tests for boundary and acceleration effects in quantum fields.

Abstract

We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the radiative properties of atoms. We calculate the rate of change of the mean atomic energy of the atom for both inertial motion and uniform acceleration. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited inertial atom to oscillate near the boundary and this oscillatory behavior may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime. While for accelerated atoms, the transitions from ground states to excited states are found to be possible even in vacuum due to changes in the vacuum fluctuations induced by both the presence of the boundary and the acceleration of atoms, and this can be regarded as an actual physical process underlying the Unruh effect.