# Coupling librational and translational motion of a levitated nanoparticle in an optical cavity

## TL;DR

This paper proposes a scheme to strongly couple librational and translational modes of a levitated nanoparticle using an optical cavity, enabling high-fidelity quantum state transfer for quantum information applications.

## Contribution

It introduces a method to couple librational and translational modes via an optical cavity, overcoming weak intrinsic coupling due to frequency mismatch.

## Key findings

- High-fidelity quantum state transfer achievable with practical parameters
- Cavity-mediated coupling enables control of nanoparticle modes
- Potential applications in quantum cooling and information processing

## Abstract

An optically levitated nonspherical nanoparticle can exhibit both librational and translational vibrations due to orientational and translational confinements of the optical tweezer, respectively. Usually, the frequency of its librational mode in a linearly-polarized optical tweezer is much larger than the frequency of its translational mode. Because of the frequency mismatch, the intrinsic coupling between librational and translational modes is very weak in vacuum. Here we propose a scheme to couple its librational and center-of-mass modes with an optical cavity mode. By adiabatically eliminating the cavity mode, the beam splitter Hamiltonian between librational and center-of-mass modes can be realized. We find that high-fidelity quantum state transfer between the librational and translational modes can be achieved with practical parameters. Our work may find applications in sympathetic cooling of multiple modes and quantum information processing.