Identify the physical mechanisms responsible for vortex removal in the vortex-comb experiments

Determine the specific physical mechanisms responsible for the removal of vortices from a highly oblate Bose–Einstein condensate during the vortex-comb protocol, in which a one-dimensional optical lattice is ramped on and off, and establish how these mechanisms operate under the experimental conditions described.

Background

The paper introduces the "vortex comb" protocol: briefly applying and removing a one-dimensional blue-detuned optical lattice to segment a highly oblate Bose–Einstein condensate into narrow channels, thereby inducing vortices to move to the condensate edge and be eliminated. Experiments demonstrate high-efficiency vortex removal without apparent heating, but the experimental setup did not allow the authors to isolate the detailed processes by which removal occurs.

Because the experimental observations alone could not pin down the mechanisms, the authors conducted extensive numerical simulations and identified several candidate mechanisms (such as peripheral channeling, vortex–antivortex annihilation, damping-induced loss, and a density–phase separation phenomenon). The open question, as explicitly stated in the experimental section, is to specifically pinpoint the physical mechanisms responsible for vortex removal under the experimental conditions.