Critical Rotation of an Annular Superfluid Bose Gas

Understand

We analyze the excitation spectrum of a superfluid Bose-Einstein condensate rotating in a ring trap.

• We identify two important branches of the spectrum related to outer and inner edge surface modes that lead to the instability of the superfluid.
• Depending on the initial circulation of the annular condensate, either the outer or the inner modes become first unstable.
• This instability is crucially related to the superfluid nature of the rotating gas.