Spontaneous emission from driven polar quantum systems

TL;DR

This paper explores how broken inversion symmetry in driven polar two-level systems alters spontaneous emission, revealing conditions for emission suppression and multiphoton processes, thus enabling advanced control over light-matter interactions.

Contribution

It introduces a polaron transformation approach to analyze spontaneous emission in driven polar systems with broken inversion symmetry, highlighting new emission control mechanisms.

Findings

Spontaneous emission can be strongly suppressed in the few-photon regime.

The ladder structure enables spontaneous absorption from the ground state.

Transition rates are governed by Bessel-function weights in the strong drive limit.

Abstract

We investigate spontaneous radiative processes in a driven polar two-level system whose interaction with the laser field is dominated by broken inversion symmetry rather than by the usual transition dipole coupling. Using a polaron transformation, we derive the dressed eigenstates of the atom-laser system and show that their longitudinal coupling reshapes the spectrum into two displaced harmonic ladders. We then analyze spontaneous transitions induced by a bosonic reservoir, and obtain transition rates that depend on both the laser parameters and the overlap between displaced field states. In the few-photon regime, we identify conditions under which spontaneous emission from the excited state can be strongly suppressed, thereby extending its lifetime, as well as regimes where the ladder structure enables spontaneous absorption from the ground state. In the semiclassical limit of a strong coherent drive, we derive compact analytical expressions for the total transition rates and show that they are governed by Bessel-function weights associated with multiphoton channels. Our results show how broken inversion symmetry qualitatively modifies decay dynamics and radiative cascades, and they establish driven polar quantum systems as a platform for controlling spontaneous light emission beyond the standard inversion-symmetric setting.