Caltech/JPL Association for Gravitational-Wave Research Seminar

Superfluid helium-4 is a quantum condensate which demonstrates frictionless steady flow. At finite frequency the attenuation for longitudinal sound is expected to be limited by the interaction with thermal phonons, limiting the quality factor to 10^11 at kilohertz frequency. We have begun experiments to parametrically couple this motion to microwave resonators (superconducting and sapphire) to form an optomechanical system. Our estimates suggest that monitering the motion at the standard quantum limit is possible and this leads to projections for extreme sensitivity to weak forces, accelerations, and perturbations of the device geometry (fractional changes of 10^-25 of the length appear detectable). We are curious about applying this device to the study of very weak forces and our hope is that this seminar might lead to new ideas and connections to the gravity community.