Researching low temperature physics:
- the physics of highly confined superfluid 3He
- disordered superfluids
- micro- and nano-mechanical resonators, their design, optimization, non-linear characteristics and the role of stress on these structures and graphene resonators
The study of superfluid 3He in aerogel
We use high Q oscillators and Helmholtz resonators to look for phase transitions and assay the superfluid fraction of 3He in aerogel in the millikelvin temperature range. We are exploring the A-B transition, effects of magnetic field to probe the nature of the superfluid as well as new anisotropic aerogels to "orient" the superfluid order parameter. We have constructed and operated a micromachined cell to probe superfuid 3He in the "2D" limit, where the superfluid is confined between two well characterized silicon/glass surfaces separated by distances on the order of a few coherence lengths. New experiments are planned using a Helmholtz flow cell. Other topics under active investigation are non-classical flow properties of confined 3He, the elastic properties of glasses (particularly silicon nitride under stress) at low temperatures, dielectric properties of glasses and also the heat capacity and thermal conductivity of high stress silicon nitride.
A second area of interest is concerned with applications and innovations with nano-electromechanical devices. This work is carried out in collaboration with Harold Craighead (A&EP). In this work we will explore and optimize the operational characteristics of NEMS/MEMS devices in ambient conditions, as well as integrate devices to CMOS circuitry in a generic process to facilitate their adoption in future applications and seek to apply these devices to sensing.
A third area of interest is in the mechanical properties of grahene resonators. The mechanical properties of the membrane can provide insight into nonlinearities. We also couple resonators to the optical field and use that coupling to tailor the mechanical properties of the membranes. This work is being carried out in collaboration with the McEuen and Craighead groups.