Non-perturbative Dynamical Casimir Effect in Optomechanical Systems: Vacuum Casimir-Rabi Splittings

TL;DR

This paper presents a fully quantum-mechanical analysis of the dynamical Casimir effect in optomechanical systems, revealing vacuum Rabi splittings, photon generation from vacuum, and entanglement, even at lower mechanical frequencies.

Contribution

It introduces a non-perturbative quantum approach to study the dynamical Casimir effect, showing photon production and entanglement without relying on high mechanical frequencies.

Findings

Photon generation from vacuum via vacuum Rabi splittings

Observation of vacuum Casimir-Rabi oscillations

Photon production possible at lower mechanical frequencies

Abstract

We study the dynamical Casimir effect using a fully quantum-mechanical description of both the cavity field and the oscillating mirror. We do not linearize the dynamics, nor do we adopt any parametric or perturbative approximation. By numerically diagonalizing the full optomechanical Hamiltonian, we show that the resonant generation of photons from the vacuum is determined by a ladder of mirror-field {\em vacuum Rabi splittings}. We find that vacuum emission can originate from the free evolution of an initial pure mechanical excited state, in analogy with the spontaneous emission from excited atoms. By considering a coherent drive of the mirror, using a master-equation approach to take losses into account, we are able to study the dynamical Casimir effect for optomechanical coupling strengths ranging from weak to ultrastrong. We find that a resonant production of photons out of the vacuum can be observed even for mechanical frequencies lower than the cavity-mode frequency. Since high mechanical frequencies, which are hard to achieve experimentally, were thought to be imperative for realizing the dynamical Casimir effect, this result removes one of the major obstacles for the observation of this long-sought effect. We also find that the dynamical Casimir effect can create entanglement between the oscillating mirror and the radiation produced by its motion in the vacuum field, and that vacuum Casimir-Rabi oscillations can occur.