Signature of Andreev-Bashkin superfluid drag from Cavity Optomechanics

The Andreev-Bashkin (AB) effect, corresponding to the dissipationless dragging of one superfluid by another, was predicted almost fifty years ago but has so far eluded experimental detection. In this work, we theoretically introduce an entirely new detection paradigm to this quest, and show that it enables the observation of the hitherto undetected AB effect for realistic parameters. We accomplish this by using the powerful techniques of cavity optomechanics, which were crucial to the observation of gravitational waves, on a spinor ring Bose-Einstein condensate. In contrast to all known AB detection methods, our scheme allows for real-time, \textit{in situ}, minimally destructive and three orders-of-magnitude more sensitive measurement of the AB effect. Our proposal, which considers persistent currents in weakly repulsive atomic condensates, and amplifies the AB signal using a novel dynamic Bragg spectroscopy technique, is supported by numerical simulations of the stochastic Gross-Pitaevski equation, which agree very well with our analytic Bogoliubov-de Gennes calculations. Our work suggests a novel tool for sensitively and nondestructively probing the dynamics of rotationally interacting superfluids using cavities and has fundamental implications for ongoing studies of superfluid hydrodynamics, atomtronics, matter-wave interferometry, and cavity optomechanical sensing.