Resonantly-paired fermionic superfluids

By V. Gurarie, L. Radzihovsky. 2006

265 citations recorded by the source corpus.

Abstract We present a theory of a degenerate atomic Fermi gas, interacting through a narrow Feshbach resonance, whose position and therefore strength can be tuned experimentally, as demonstrated recently in ultracold trapped atomic gases. The distinguishing feature of the theory is that its accuracy is controlled by a dimensionless parameter proportional to the ratio of the width of the resonance to Fermi energy. The theory is therefore quantitatively accurate for a narrow Feshbach resonance. In the case of a narrow s-wave resonance, our analysis leads to a quantitative description of the crossover between a weakly paired BCS superconductor of overlapping Cooper pairs and a strongly paired molecular Bose–Einstein condensate of diatomic molecules. In the case of pairing via a p-wave resonance, that we show is always narrow for a sufficiently low density, we predict a detuning-temperature phase diagram, that in the course of a BCS–BEC crossover can exhibit a host of thermodynamically distinct phases separated by quantum and classical phase transitions. For an intermediate strength of the dipolar anisotropy, the system exhibits a px + ipy paired superfluidity that undergoes a topological phase transition between a weakly coupled gapless ground state at large positive detuning and a strongly paired fully gapped molecular superfluid for a negative detuning. In two dimensions the former state is characterized by a Pfaffian ground state exhibiting topological order and non-Abelian vortex excitations familiar from fractional quantum Hall systems.

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

View Paper: https://www.semanticscholar.org/paper/09a27c0eb9af47c55d4daa582227372638f1e0b4

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In Atomic and Molecular Physics, and Optics

In Condensed Matter Physics

Citations in the corpus

Fermi gases in one dimension: From Bethe ansatz to experiments (2013, background): “…regard, across a narrow resonance, the 1D effective potential is determined by not only the scattering length, but also the effective range which is introduced by a strong energy-dependent scattering amplitude of two colliding atoms (Cui, 2012a; Gurarie and Radzihovsky, 2007; Qi and Guan, 2012).”
Topological bands for ultracold atoms (2018, unknown): “These include methods involving a p-wave Feshbach resonance (Gurarie and Radzihovsky, 2007), or long-range dipolar interactions (Baranov et al., 2012), or induced interactions via a background BEC (Wu and Bruun, 2016).”
Theory of ultracold atomic Fermi gases (2007, methodology): “…the effective range |R∗| of the interatomic potential becomes of the order of the inverse Fermi wavevector, as happens in the case of narrow Feshbach resonances, more complex effective potentials should be introduced in the solution of the many-body problem (see e.g. Gurarie and Radzihovsky, 2007).”
Rapidly rotating atomic gases (2008, background): “The quantity a 3 1 is often referred to as the “scattering volume”[208], the modulus of which diverges at the position of the resonance.”