# Anti-Dynamical Casimir Effect as a Resource for Work Extraction

## TL;DR

This paper explores how the anti-dynamical Casimir effect in a quantum Rabi model can be used to extract significant work from vacuum excitations through finite-time modulation protocols, with practical control considerations.

## Contribution

It demonstrates that the anti-dynamical Casimir effect enables substantial work extraction from a quantum system, surpassing modulation amplitude limits, and offers methods for experimental control.

## Key findings

- Work extracted can greatly exceed modulation amplitude.
- Finite-time protocols enable out-of-equilibrium work extraction.
- Practical control methods are proposed for experimental setups.

## Abstract

We consider the quantum Rabi model with external time modulation of the atomic frequency, which can be employed to create excitations from the vacuum state of the electromagnetic field as a consequence of the dynamical Casimir effect. Excitations can also be systematically subtracted from the atom-field system by suitably adjusting the modulation frequency, in the so-called anti-dynamical Casimir effect (ADCE). We evaluate the quantum thermodynamical work and show that a realistic out-of-equilibrium finite-time protocol harnessing ADCE allows for work extraction from the system, whose amount can be much bigger then the modulation amplitude, $| W_{\mathrm{ADCE}}| \gg \hbar \epsilon_\Omega$, in contrast to the case of very slow adiabatic modulations. We provide means to control work extraction in state-of-the-art experimental scenarios, where precise frequency adjustments or complete system isolation may be difficult to attain.