# Dynamical Casimir effect and state transfer in the ultrastrong coupling regime

## TL;DR

This paper investigates how the dynamical Casimir effect in the ultrastrong coupling regime impacts quantum state transfer, revealing fundamental limitations and suggesting the need for new quantum gate schemes.

## Contribution

It demonstrates that the dynamical Casimir effect constrains quantum protocols in the ultrastrong coupling regime and highlights the necessity for alternative approaches.

## Key findings

- DCE arises in the USC regime due to nonadiabatic parameter changes.
- Standard quantum protocols are limited by DCE in high-fidelity operations.
- New schemes are needed for ultrafast quantum gates in the USC regime.

## Abstract

The dynamical Casimir effect (DCE) manifests itself in the ultrastrong matter-field coupling (USC) regime, as a consequence of the nonadiabatic change of some parameters of a system. We show that the DCE is a fundamental limitation for standard quantum protocols based on quantum Rabi oscillations, implying that new schemes are required to implement high-fidelity ultrafast quantum gates. Our results are illustrated by means of a paradigmatic quantum communication protocol, i.e., quantum state transfer.