Grant: Discovery Grants Program - Individual

Advances in condensed matter physics closely follow advances in measurement technology, and there is no greater advance in measurement technology over the last decade than that of cavity optomechanics. Cavity optomechanics (electromechanics) describes the engineered coupling of an optical (microwave) cavity to a mechanical resonator, which leads to a dramatic improvement in the scattering rate between photons and phonons, and hence determination of the mechanical motion. Cavity optomechanics is being used to test the limits of quantum mechanics and develop amazing new quantum technologies, but surprisingly has barely been applied to the study of condensed matter physics. Over the last 12 years, my group has advanced the techniques of cavity optomechanics at low temperatures and is set to embark on an ambitious program of cavity optomechanical studies of quantum condensed matter, specifically targeting superconductors and superfluids. We are the world leading group in torsional optomechanics and have achieved a record setting torque sensitivity. Under the current proposal, we will extend our optomechanical torque platform to perform real-time measurements of individual superconducting vortices, and observe the collective dynamics of a vortex lattice in a superconductor for the first time. This will allow study of the temporal dynamics of unusual phenomena such as giant multiply quantized vortices for the first time, watch the transitions between vortex configurations, and explore unconventional superconductors. In addition, our group has developed an advanced platform for the study of superfluids confined to the nanoscale based on a unique superfluid electromechanical resonator. Here, we propose to use this platform to observe single excitations in the superfluid, and push deeper into the 2D realm to explore topological physics such as the Kosterlitz-Thouless transition and 2D vortices. We will also use our superfluid electromechanical resonator to study the effects of confinement on superfluid 3He. We have built Canada's only adiabatic nuclear demagnetization refrigerator to achieve the sub-millikelvin temperatures required for superfluid 3He. Combined with our 2D technology we will explore a new superfluid state, that we recently mapped out the phase diagram for the first time, which is believed to be a `superfluid crystal', or pair-density wave state. We will also explore exotic topological defects in superfluid 3He, and work to stabilize other new phases via engineered confinement, arguably the most important topics in quantum fluids. Long term, we will use our cryogenic and nanofabrication expertise, with cavity optomechanics, to explore some of the deepest questions of quantum condensed matter, such as uncovering the pairing state in unconventional superconductors; exploring pair-density wave states, Majorana fermions, and supersymmetry-like physics in topological superfluids; and searching for the last undiscovered elemental superfluid.