Superfluid rotation sensor with helical laser trap

Abstract

The macroscopic quantum states of the dilute bosonic ensemble in helical laser trap at the temperatures about $10^{-6}\bf {K}$ are considered in the framework of the Gross-Pitaevskii equation. The helical interference pattern is composed of the two counter propagating Laguerre-Gaussian optical vortices with opposite orbital angular momenta $\ell \hbar$ and this pattern is driven in rotation via angular Doppler effect. Macroscopic observables including linear momentum and angular momentum of the atomic cloud are evaluated explicitly. It is shown that rotation of reference frame is transformed into translational motion of the twisted matter wave. The speed of translation equals the group velocity of twisted wavetrain $V_z= \Omega\ell/ k$ and alternates with a sign of the frame angular velocity $\Omega$ and helical pattern handedness $\ell$. We address detection of this effect using currently accessible laboratory equipment with emphasis on the difference between quantum and classical fluids.