Quantum enhanced feedback cooling of a mechanical oscillator

TL;DR

This paper demonstrates the first implementation of quantum feedback control of a mechanical oscillator using a squeezed light probe, achieving enhanced cooling and lower temperatures than classical methods, with implications for quantum technologies.

Contribution

First experimental realization of quantum feedback cooling of a mechanical oscillator using a squeezed light probe, surpassing classical measurement limits.

Findings

Quantum feedback control with squeezed light improves cooling efficiency.

Achieved lower oscillator temperatures than classical feedback methods.

Demonstrated measurement rate surpassing classical limits.

Abstract

Laser cooling is a fundamental technique used in primary atomic frequency standards, quantum computers, quantum condensed matter physics and tests of fundamental physics, among other areas. It has been known since the early 1990s that laser cooling can, in principle, be improved by using squeezed light as an electromagnetic reservoir; while quantum feedback control using a squeezed light probe is also predicted to allow improved cooling. Here, we implement quantum feedback control of a micro-mechanical oscillator for the first time with a squeezed probe field. This allows quantum-enhanced feedback cooling with a measurement rate greater than it is possible with classical light, and a consequent reduction in the final oscillator temperature. Our results have significance for future applications in areas ranging from quantum information networks, to quantum-enhanced force and displacement measurements and fundamental tests of macroscopic quantum mechanics.