Observation of the scissors mode and superfluidity of a trapped Bose-Einstein condensed gas

TL;DR

This paper reports the observation of the scissors mode in a Bose-Einstein condensate of rubidium atoms, providing direct evidence of superfluidity through characteristic oscillation behaviors.

Contribution

It presents the first experimental observation of the scissors mode in a BEC, demonstrating superfluid properties via oscillation frequency analysis.

Findings

Normal fluid exhibits two oscillation frequencies.

Superfluid condensate oscillates at a single frequency without damping.

Scissors mode confirms superfluidity in BEC.

Abstract

We report the observation of the scissors mode of a Bose-Einstein condensed gas of 87^Rb atoms in a magnetic trap, which gives direct evidence of superfluidity in this system. The scissors mode of oscillation is excited by a sudden rotation of the anisotropic trapping potential. For a gas above T_c (normal fluid) we detect the occurrence of oscillations at two frequencies, with the lower frequency corresponding to the rigid body value of the moment of inertia. Well below T_c the condensate oscillates at a single frequency, without damping, as expected for a superfluid.