Performance and limits of feedback cooling methods for levitated oscillators: a direct comparison

TL;DR

This paper compares parametric and velocity feedback damping methods for cooling levitated oscillators, demonstrating that velocity damping achieves lower temperatures and is more robust under experimental imperfections.

Contribution

It provides a direct experimental comparison of two popular feedback cooling methods on the same particle and detection system, highlighting the superior performance of velocity damping.

Findings

Velocity damping cools to lower temperatures than parametric damping.

Velocity damping is more resilient to experimental imperfections.

Results align with analytical and numerical models including noise.

Abstract

Cooling the centre-of-mass motion is an important tool for levitated optomechanical systems, but it is often not clear which method can practically reach lower temperatures for a particular experiment. We directly compare the parametric and velocity feedback damping methods, which are used extensively for cooling the motion of single trapped particles in a range of traps. By performing experiments on the same particle, and with the same detection system, we demonstrate that velocity damping cools the oscillator to lower temperatures and is more resilient to imperfect experimental conditions. We show that these results are consistent with analytical limits as well as numerical simulations that include experimental noise.