title: Kibble-Zurek scaling and its breakdown for spontaneous generation of Josephson vortices in Bose-Einstein condensates.
abstract: Atomic Bose-Einstein condensates confined to a dual-ring trap support Josephson vortices as topologically stable defects in the relative phase. We propose a test of the scaling laws for defect formation by quenching a Bose gas to degeneracy in this geometry. Stochastic Gross-Pitaevskii simulations reveal a -1/4 power-law scaling of defect number with quench time for fast quenches, consistent with the Kibble-Zurek mechanism. Slow quenches show stronger quench-time dependence that is explained by the stability properties of Josephson vortices, revealing the boundary of the Kibble-Zurek regime. Interference of the two atomic fields enables clear long-time measurement of stable defects and a direct test of the Kibble-Zurek mechanism in Bose-Einstein condensation.
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Shih-Wei
authors.initials: SW
authors.lastname: Su
authors.forename: Shih-Chuan
authors.initials: SC
authors.lastname: Gou
authors.forename: Ashton
authors.initials: A
authors.lastname: Bradley
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Fialko
authors.forename: Joachim
authors.initials: J
authors.lastname: Brand