# Cooling of a levitated nanoparticle with digital parametric feedback

## TL;DR

This paper demonstrates a digital parametric feedback method to cool a levitated nanoparticle's motion to millikelvin temperatures, enabling precise digital control for advanced applications.

## Contribution

It introduces a novel digital feedback cooling technique using laser intensity switching, enhancing control over nanoparticle motion in optical levitation.

## Key findings

- Achieved cooling to dozens of millikelvin.
- Effect of modulation parameters on cooling efficiency analyzed.
- Method enables programmable digital control of nanoparticle motion.

## Abstract

The motion control of a levitated nanoparticle plays a central role in optical levitation for fundamental studies and practical applications. Here, we presented a digital parametric feedback cooling based on switching between two trapping laser intensity levels with square wave modulations. The effects of modulation depth and modulation signal phase on the cooling result were investigated in detail. With such a digital parametric feedback method, the centre-of-mass temperature of all three motional degrees of freedom can be cooled to dozens of milli-Kelvin, which paved the way to fully control the motion of the levitated nanoparticle with a programmable digital process for wild applications.