We have analyzed a single vortex at T=0 in a 3D superfluid atomic Fermi gas across a Feshbach resonance. On the BCS side, the order parameter varies on two scales: k(F)(-1)and the coherence length xi, while only variation on the scale of xi is seen away from the BCS limit. The circulating current has a peak value jmax which is a nonmonotonic function of 1/k(F)a(s) implying a maximum critical velocity approximately v(F) at unitarity. The number of fermionic bound states in the core decreases as we move from the BCS to the BEC regime. Remarkably, a bound state branch persists even on the BEC side reflecting the composite nature of bosonic molecules.We have analyzed a single vortex at T=0 in a 3D superfluid atomic Fermi gas across a Feshbach resonance. On the BCS side, the order parameter varies on two scales: k(F)(-1)and the coherence length xi, while only variation on the scale of xi is seen away from the BCS limit. The circulating current has a peak value jmax which is a nonmonotonic function of 1/k(F)a(s) implying a maximum critical velocity approximately v(F) at unitarity. The number of fermionic bound states in the core decreases as we move from the BCS to the BEC regime. Remarkably, a bound state branch persists even on the BEC side reflecting the composite nature of bosonic molecules.

arXiv:cond-mat/0510761Physical Review LettersMar 9, 2006118 citations

Fermion Pairing and BEC-BCS Crossover in Novel Systems

Renyuan Liao

Jan 1, 20080 citations

Core structure of two-dimensional Fermi gas vortices in the BEC-BCS crossover region

Lucas Madeira, Stefano Gandolfi, Kevin E. Schmidt

We report $T=0$ diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. We investigate how vortex core structure properties behave over the BEC-BCS crossover. We calculate the vortex excitation energy, density profiles, and vortex core properties related to the current. We find a density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit. Size-effect dependencies in the disk geometry were carefully studied.We report $T=0$ diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. We investigate how vortex core structure properties behave over the BEC-BCS crossover. We calculate the vortex excitation energy, density profiles, and vortex core properties related to the current. We find a density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit. Size-effect dependencies in the disk geometry were carefully studied.

arXiv:1703.01998Physical Review AMay 2, 201716 citations

Probing the BCS-BEC crossover with persistent currents

Giovanni Pecci, Piero Naldesi, Luigi Amico A +1 more

We study the persistent currents of an attractive Fermi gas confined in a tightly confining ring trap and subjected to an artificial gauge field all through the BCS-BEC crossover.At weak attractions, on the Bardeen-Cooper-Schrieffer (BCS) side, fermions display a parity effect in the persistent currents, i.e., their response to the gauge field is paramagnetic or diamagnetic depending on the number of pairs on the ring.At resonance and on the Bose-Einstein condensate (BEC) side of the crossover we find a doubling of the periodicity of the ground-state energy as a function of the artificial gauge field and disappearance of the parity effect, indicating that persistent currents can be used to infer the formation of tightly bound bosonic pairs.Our predictions can be accessed in ultracold atom experiments through noise interferograms.We study the persistent currents of an attractive Fermi gas confined in a tightly confining ring trap and subjected to an artificial gauge field all through the BCS-BEC crossover.At weak attractions, on the Bardeen-Cooper-Schrieffer (BCS) side, fermions display a parity effect in the persistent currents, i.e., their response to the gauge field is paramagnetic or diamagnetic depending on the number of pairs on the ring.At resonance and on the Bose-Einstein condensate (BEC) side of the crossover we find a doubling of the periodicity of the ground-state energy as a function of the artificial gauge field and disappearance of the parity effect, indicating that persistent currents can be used to infer the formation of tightly bound bosonic pairs.Our predictions can be accessed in ultracold atom experiments through noise interferograms.

arXiv:2010.03552Physical Review ResearchSep 14, 202124 citations

Superfluid properties across the BEC/BCS transition

Jacques Tempere, Jozef T. Devreese

Bulletin of the American Physical SocietyMar 14, 20060 citations

We report

T=0

diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. We investigate how vortex core structure properties behave over the BEC-BCS crossover. We calculate the vortex excitation energy, density profiles, and vortex core properties related to the current. We find a density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit. Size-effect dependencies in the disk geometry were carefully studied.