Bound states in a superfluid vortex: A detailed study along the BCS-BEC crossover
Authors: Simonucci S., Pieri P., Strinati Calvanese G.
Autors Affiliation: Univ Camerino, Phys Div, Sch Sci & Technol, I-62032 Camerino, MC, Italy; INFN, Sez Perugia, I-06123 Perugia, PG, Italy; Ist Nazl Ottica, CNR INO, Sede Firenze, I-50125 Florence, FI, Italy
Abstract: The bound states that can occur in a superfluid vortex have recently called for attention owing to the capability of detecting them experimentally. However, a detailed theoretical account for the presence of these vortex bound states is still lacking for all temperatures in the superfluid phase and couplings along the BCS-BEC crossover. Here, we fill this gap and present a systematic theoretical study based on the Bogoliubov-de Gennes equations for the bound states that occur over the two characteristic (inner and outer) spatial ranges in which the extension of a superfluid vortex can be partitioned. It is found that the total number of bound states decreases from the BCS (weak-coupling) side of the crossover toward the intermediate-coupling region where they are still present, whereas the bound states disappear upon entering the BEC (strong-coupling) side. A scaling relation is also obtained that connects the number of bound states in the inner spatial range of the vortex to the depth and width of the vortex itself. A criterion is finally provided in terms of the local density of states, to distinguish where a given fermionic superfluid is located in the coupling-temperature phase diagram of the BCS-BEC crossover.
Journal/Review: PHYSICAL REVIEW B
Volume: 99 (13) Pages from: 134506-1 to: 134506-10