Coherent Resonant Coupling between Atoms and a Mechanical Oscillator Mediated by Cavity-Vacuum Fluctuations

TL;DR

This paper demonstrates how quantum vacuum fluctuations enable coherent energy transfer between an atom and a mechanical oscillator in a hybrid cavity system, revealing complex virtual processes and potential for photon conversion.

Contribution

It introduces a theoretical framework for atom-mechanical coupling via vacuum fluctuations, highlighting high-order virtual processes and multi-atom interactions in cavity optomechanics.

Findings

Resonant atom-mirror coupling arises from high-order virtual pair-creation processes.

Photon frequency conversion can be achieved within multi-mode cavities.

Two atoms can simultaneously absorb a single mechanical excitation.

Abstract

We show that an atom can be coupled to a mechanical oscillator via quantum vacuum fluctuations of a cavity field enabling energy transfer processes between them. In a hybrid quantum system consisting of a cavity resonator with a movable mirror and an atom, these processes are dominated by two pair-creation mechanisms: the counterrotating (atom-cavity system) and dynamical Casimir interaction terms (optomechanical system). Because of these two pair-creation mechanisms, the resonant atom-mirror coupling is the result of high-order virtual processes with different transition paths well described in our theoretical framework. We perform a unitary transformation to the atom-mirror system Hamiltonian, exhibiting two kinds of multiple-order transitions of the pair creation. By tuning the frequency of the atom, we show that photon frequency conversion can be realized within a cavity of multiple modes. Furthermore, when involving two atoms coupled to the same mechanical mode, a single vibrating excitation of the mechanical oscillator can be simultaneously absorbed by the two atoms. Considering recent advances in strong and ultrastrong coupling for cavity optomechanics and other systems, we believe our proposals can be implemented using available technology.