Project Level: Honours/Masters

Phonons propagating in a uniform medium tend to have a linear dispersion relationship, which means the speed at which the phonons propagate is independent of wavelength and the energy of the phonons is directly proportional to their frequency. While this is useful and desirable when transmitting phonon wave packets over long distances, it can be detrimental to proposed applications of standing wave phonons, such as in phononic waveguides for measuring rotation that require long phonon lifetimes. Even at absolute zero temperature, the linear dispersion of phonons means there are many scattering channels, limiting the usefulness of these architectures.

In acoustic circuits this limitation can be overcome by engineering the dispersion relationship to be nonlinear in the system/waveguide through elements such as filters, which limit the scattering channels into which the phonons can decay, and greatly increase the standing wave lifetime.

This project aims to implement such classical phononic band-pass filters in a superfluid system, hopefullying a demonstrate a significant improvement in the lifetime of phononic standing waves over linear waveguides. These result would have significant impact on improving the viability of superfluid rotation sensors based on phononic excitations.

Project members

Dr Tyler Neely

ARC Future Fellowship
School of Mathematics and Physics