Lower limit on the achievable temperature in resonator-based sideband cooling

TL;DR

This paper establishes a fundamental lower temperature limit in resonator-based sideband cooling, highlighting that practical decay rates prevent reaching the quantum limit in realistic experiments.

Contribution

It introduces a previously unconsidered lower temperature bound in resonator cooling, emphasizing the importance of resonator decay rate in achieving effective cooling.

Findings

Lower temperature limit T* can be higher than the quantum limit.

Resonator decay rate must exceed the cooled oscillator's decay rate.

Effective cooling requires specific decay rate conditions.

Abstract

A resonator can be effectively used as a cooler for another linear oscillator with a much smaller frequency. A huge cooling effect, which could be used to cool a mechanical oscillator below the energy of quantum fluctuations, has been predicted by several authors. However, here we show that there is a lower limit T* on the achievable temperature that was not considered in previous works and can be higher than the quantum limit in realistic experimental realizations. We also point out that the decay rate of the resonator, which previous studies stress should be small, must be larger than the decay rate of the cooled oscillator for effective cooling.