Cavity optomechanics with superfluid helium

Speaker: Dr Chris Baker
Affiliation: University of Queensland, School of Mathematics and Physics

Abstract

Cavity optomechanics focuses on the interaction between confined light and a mechanical degree of freedom. This field has a broad range of applications ranging from high-precision acceleration, force and magnetic sensing to the Nobel-prize winning observation of gravitational waves emitted from a binary black hole merger. In this colloquium I will start by providing an introductory overview of the field of cavity optomechanics, before touching upon research carried out at UQ interfacing cavity optomechanics and superfluid physics [1]. I will present new experimental results where we employ nanofabricated silicon photonic crystal structures to create an optically addressable wave tank containing a few femtoliters of superfluid helium. The superfluid film's minute thickness (roughly 20 atomic monolayers) compared to the wave tank's dimension allows us to investigate nonlinear hydrodynamic flows in regimes exceeding those of the most extreme terrestrial phenomena such as tsunamis. This novel platform enables us to generate and measure a rich variety of nonlinear phenomena, including backwards 'crashing' third sound waves, modulational instability/dissipative solitonic structures [2] and superfluid shock waves.

[1] A. Sawadsky et al., Science Advances 9, eade3591 (2023); W. W. Wasserman et al., Opt. Express, 30, 30822 (2022);

X. He et al., Nature Physics 16, 4 (2020); Y. P. Sachkou et al., Science 366, 1480 (2019).

[2] J. Zhang et al., Optomechanical Dissipative Solitons, Nature 600, 75 (2021).