# Optomechanics with Levitated Particles

## TL;DR

Levitated optomechanics uses light to control and cool microscopic particles, enabling advanced sensing and quantum experiments with potential for creating macroscopic quantum superpositions.

## Contribution

This paper reviews the recent progress in levitated optomechanics, highlighting its potential for quantum physics and sensing applications, and discusses techniques for cooling and manipulating levitated particles.

## Key findings

- Levitated particles can be cooled below 1 mK using optical feedback.
- Levitated optomechanics enables high-precision force sensing.
- Potential for creating macroscopic quantum superpositions at high masses.

## Abstract

Optomechanics is concerned with the use of light to control mechanical objects. As a field, it has been hugely successful in the production of precise and novel sensors, the development of low-dissipation nanomechanical devices, and the manipulation of quantum signals. Micro- and nano-particles levitated in optical fields act as nanoscale oscillators, making them excellent low-dissipation optomechanical objects, with minimal thermal contact to the environment when operating in vacuum. Levitated optomechanics is seen as the most promising route for studying high-mass quantum physics, with the promise of creating macroscopically separated superposition states at masses of $10^6$ amu and above. Optical feedback, both using active monitoring or the passive interaction with an optical cavity, can be used to cool the centre-of-mass of levitated nanoparticles well below 1 mK, paving the way to operation in the quantum regime. In addition, trapped mesoscopic particles are the paradigmatic system for studying nanoscale stochastic processes, and have already demonstrated their utility in state-of-the-art force sensing.