Quantum optomechanics in a liquid

TL;DR

This paper demonstrates quantum behavior in the vibrations of a superfluid liquid helium, revealing zero-point motion and back-action, thus opening new avenues for quantum optomechanics using liquids.

Contribution

First observation of quantum effects in liquid-based optomechanical systems, expanding the scope beyond solids and gases.

Findings

Detection of zero-point motion in superfluid helium vibrations

Observation of measurement back-action in liquid optomechanics

Potential for exploring new quantum regimes with liquids

Abstract

Optomechanical systems provide a means for studying and controlling quantum effects in the motion of macroscopic objects. To date, quantum optomechanical effects have been studied in objects made from solids and gases. Here we describe measurements of quantum behavior in the vibrations of a liquid body. Specifically, we monitor the fluctuations of an individual acoustic standing wave in superfluid liquid helium, and find that it displays the characteristic signatures of zero-point motion and measurement back-action. This opens the possibility of exploiting the properties of liquids in general (and superfluid helium in particular) to access qualitatively new regimes of quantum optomechanics.