# Cold Damping of an Optically Levitated Nanoparticle to micro-Kelvin Temperatures

## TL;DR

This paper demonstrates a feedback cooling technique that reduces the temperature of an optically levitated nanoparticle to 100 micro-Kelvin, approaching ground-state conditions, with results matching theoretical models.

## Contribution

The study achieves record-low temperatures in nanoparticle cooling using cold damping, providing a detailed model and a pathway toward ground-state cooling.

## Key findings

- Achieved nanoparticle cooling to 100 micro-Kelvin.
- Measured and confirmed the temperature dependence on feedback gain.
- Provided a roadmap for reaching quantum ground state.

## Abstract

We implement a cold damping scheme to cool one mode of the center-of-mass motion of an optically levitated nanoparticle in ultrahigh vacuum from room temperature to a record-low temperature of 100 micro-Kelvin. The measured temperature dependence on feedback gain and thermal decoherence rate is in excellent agreement with a parameter-free model. We determine the imprecision-backaction product for our system and provide a roadmap towards ground-state cooling of optically levitated nanoparticles.