Characterization of a Drop of Superfluid Helium Levitated in Vacuum*

Optomechanical systems, in which light interacts with mechanical vibrations, exhibit fascinating nonlinear phenomena that can provide access to the quantum behavior of macroscopic objects. Superfluid liquid helium is a promising material in which to access new regimes of quantum optomechanics, owing to its extremely low optical and mechanical dissipation, its high thermal conductivity, its ability cool itself via evaporation, and its unconventional degrees of freedom (such as vortices and ripplons). In order to construct an optomechanical system made entirely of superfluid He, we have magnetically levitated mm-scale drops of liquid helium in vacuum. Magnetic levitation is expected to remove an important source of dissipation by allowing the device’s mechanical energy and optical energy to be stored entirely within the superfluid drop (in the drop’s surface waves and optical whispering gallery modes, respectively). We will describe characterizations of the levitated drop’s optical, mechanical, and thermal properties.