Cooling a harmonic oscillator by optomechanical modification of its bath

TL;DR

This paper proposes a novel optomechanical cooling method that reduces both the thermal load and enhances the quality factor of a mechanical resonator by dynamically modifying its damping mechanism through optical interactions.

Contribution

It introduces a new cooling scheme that simultaneously lowers temperature and improves quality factor by optomechanically modifying the resonator's damping mechanism.

Findings

The proposed scheme can reduce the effective temperature of the mechanical mode.

It can enhance the mechanical quality factor.

A realistic design for implementation is identified.

Abstract

Optomechanical systems show tremendous promise for high sensitivity sensing of forces and modification of mechanical properties via light. For example, similar to neutral atoms and trapped ions, laser cooling of mechanical motion by radiation pressure can take single mechanical modes to their ground state. Conventional optomechanical cooling is able to introduce additional damping channel to mechanical motion, while keeping its thermal noise at the same level, and as a consequence, the effective temperature of the mechanical mode is lowered. However, the ratio of temperature to quality factor remains roughly constant, preventing dramatic advances in quantum sensing using this approach. Here we propose an approach for simultaneously reducing the thermal load on a mechanical resonator while improving its quality factor. In essence, we use the optical interaction to dynamically modify the dominant damping mechanism, providing an optomechanically-induced effect analogous to a phononic band gap. The mechanical mode of interest is assumed to be weakly coupled to its heat bath but strongly coupled to a second mechanical mode, which is cooled by radiation pressure coupling to a red detuned cavity field. We also identify a realistic optomechanical design that has the potential to realize this novel cooling scheme.