BEC–BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids

By D. Sheehy, L. Radzihovsky. 2006

163 citations recorded by the source corpus.

Abstract We study resonantly-paired s-wave superfluidity in a degenerate gas of two species (hyperfine states labeled by ↑, ↓) of fermionic atoms when the numbers N↑ and N↓ of the two species are unequal, i.e., the system is “polarized.” We find that the continuous crossover from the Bose–Einstein condensate (BEC) limit of tightly-bound diatomic molecules to the Bardeen–Cooper–Schrieffer (BCS) limit of weakly correlated Cooper pairs, studied extensively at equal populations, is interrupted by a variety of distinct phenomena under an imposed population difference ΔN ≡ N↑ − N↓. Our findings are summarized by a “polarization” (ΔN) versus Feshbach-resonance detuning (δ) zero-temperature phase diagram, which exhibits regions of phase separation, a periodic FFLO superfluid, a polarized normal Fermi gas and a polarized molecular superfluid consisting of a molecular condensate and a fully polarized Fermi gas. We describe numerous experimental signatures of such phases and the transitions between them, in particular focusing on their spatial structure in the inhomogeneous environment of an atomic trap.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/0b08f36f1f19fe9bfd5a3474d1778ba5756104e0

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In Atomic and Molecular Physics, and Optics

In Condensed Matter Physics

Citations in the corpus

Making, probing and understanding ultracold Fermi gases (2008, background): “As we will show, the ratio EF /E0 of the Fermi energy to the coupling energy scale is the parameter that decides whether the physics around the resonance is universal (E0 ≫ EF ) or whether the closed molecular channel still plays a role (E0 ≪ EF ) [264, 265, 266, 247].”
Colloquium : Nonequilibrium effects in superconductors with a spin-splitting field (2017, background): “The FFLO state has been also studied in the context 14 of heavy-fermion superconductors (Gloos et al., 1993) and ultra-cold Fermi gases (Kinnunen et al., 2017; Koponen et al., 2007; Korolyuk et al., 2010) especially in the context of the BCS-BEC crossover (Sheehy and Radzihovsky, 2006, 2007).”
Theory of ultracold atomic Fermi gases (2007, background): “A major question is whether the FFLO phase survives when correlations are stronger and if it can be realized in trapped configurations (Mizushima, Machida and Ichioka, 2005; Sheehy and Radzihovsky 2007; Yoshida and Yip, 2007).”