Highly Polarized Fermi Gases across a Narrow Feshbach Resonance

Abstract

We address the phase of a highly polarized Fermi gas across a narrow Feshbach resonance starting from the problem of a single down spin fermion immersed in a Fermi sea of up spins. Both polaron and pairing states are considered using the variational wave function approach, and we find that the polaron to pairing transition will take place at the BCS side of the resonance, strongly in contrast to a wide resonance where the transition is located at the BEC side. For pairing phase, we find out the critical strength of repulsive interaction between pairs above which the mixture of pairs and fermions will not phase separate. Therefore, nearby a narrow resonance, it is quite likely that magnetism can coexist with s-wave BCS superfluidity at large Zeeman field, which is a remarkable property absent in conventional BCS superconductors (or fermion pair superfluids).

4.5 pages with 4 figures plus 2.5 pages with one figure of supplementary material, typos corrected, references updated

References in corpus (13)

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Cited by in corpus (16)

• Polarons, Dressed Molecules, and Itinerant Ferromagnetism in ultracold Fermi gases
• Universality of an impurity in a Bose-Einstein condensate
• Quantum dynamics of impurities coupled to a Fermi sea
• Observation of a Strong Atom-Dimer Attraction in a Mass-Imbalanced Fermi-Fermi Mixture
• Stability and breakdown of Fermi polarons in a strongly interacting Fermi-Bose mixture
• An impurity in a Fermi sea on a narrow Feshbach resonance: A variational study of the polaronic and dimeronic branches
• Polarons and dressed molecules near narrow Feshbach resonances
• New type of crossover physics in three-component Fermi gases
• High-precision numerical solution of the Fermi polaron problem and large-order behavior of its diagrammatic series
• The p-wave polaron
• Two-band description of resonant superfluidity in atomic Fermi gases
• The self-energy of an impurity in an ideal Fermi gas to second order in the interaction strength
• Highly polarized one-dimensional Fermi gases near a narrow $p-$wave resonance
• Polaronic and dressed molecular states in orbital Feshbach resonances
• Impurity with a resonance in the vicinity of the Fermi energy
• Local manipulation of quantum magnetism in 1D ultracold Fermi gases across narrow resonances