2011/12/31 by Stuart Moulder, Scott Beattie, Robert P. Smith +2 · 2 citations
Physics and Astronomy · #cond-mat.quant-gas #physics.atom-ph #quant-ph
paper · pdf · doi:10.1103/physreva.86.013629
published as Phys. Rev. A 86, 013629 (2012) · 7 pages, 8 figures; expanded version, including numerical simulations
arxiv created 2012/06/05 · arxiv updated 2012/07/24
We study the metastability and decay of multiply-charged superflow in a ring-shaped atomic Bose-Einstein condensate. Supercurrent corresponding to a giant vortex with topological charge up to q=10 is phase-imprinted optically and detected both interferometrically and kinematically. We observe q=3 superflow persisting for up to a minute and clearly resolve a cascade of quantised steps in its decay. These stochastic decay events, associated with vortex-induced 2 π phase slips, correspond to collective jumps of atoms between discrete q values. We demonstrate the ability to detect quantised rotational states with > 99 % fidelity, which allows a detailed quantitative study of time-resolved phase-slip dynamics. We find that the supercurrent decays rapidly if the superflow speed exceeds a critical velocity in good agreement with numerical simulations, and we also observe rare stochastic phase slips for superflow speeds below the critical velocity.