Continuous vortices and collective excitations in ferromagnetic spinor Bose–Einstein condensates

Abstract

Bose–Einstein condensates (BEC) realized in alkali atomic gases with the hyperfine state F=1 keep “spin” states degenerate and active under an optical trap. These systems, so-called spinor BEC are analogous to the A-phase of the superfluid 3 He . Among various topological structures, the Mermin–Ho and Anderson–Toulouse vortices are proposed in superfluid 3 He-A phase. We demonstrate by solving the extended Gross–Pitaevskii equation that these topological structures are thermodynamically stable in ferromagnetic spinor BEC under rotation. Furthermore, we show the collective modes for such the vortices within Bogoliubov theory.