Spontaneous emission from a two--level atom tunneling in a double--well potential

TL;DR

This paper analyzes how a two-level atom tunneling in a double-well potential interacts with electromagnetic radiation, revealing conditions for decoherence and interference effects in emitted light.

Contribution

It provides a comprehensive analysis of spontaneous emission and tunneling dynamics of a two-level atom in a double-well potential, including interference effects and decoherence conditions.

Findings

Interference fringes appear in emitted light when wavelength is comparable to well separation.

Decoherence depends on the relation between emission wavelength and tunneling parameters.

External and internal degrees of freedom couple during photon emission, affecting the atom's dynamics.

Abstract

We study a two-level atom in a double--well potential coupled to a continuum of electromagnetic modes (black body radiation in three dimensions at zero absolute temperature). Internal and external degrees of the atom couple due to recoil during emission of a photon. We provide a full analysis of the problem in the long wavelengths limit up to the border of the Lamb-Dicke regime, including a study of the internal dynamics of the atom (spontaneous emission), the tunneling motion, and the electric field of the emitted photon. The tunneling process itself may or may not decohere depending on the wavelength corresponding to the internal transition compared to the distance between the two wells of the external potential, as well as on the spontaneous emission rate compared to the tunneling frequency. Interference fringes appear in the emitted light from a tunneling atom, or an atom in a stationary coherent superposition of its center--of--mass motion, if the wavelength is comparable to the well separation, but only if the external state of the atom is post-selected.