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Title: Resonantly paired fermionic superfluids

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 p {sub x} + ip {sub y} paired superfluidity that undergoes a topological phase transition between a weakly coupled gapless ground state at large positive detuning and amore » 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.« less

Authors:
 [1];  [2]
  1. Department of Physics, University of Colorado, Boulder, CO 80309 (United States). E-mail: victor.gurarie@colorado.edu
  2. Department of Physics, University of Colorado, Boulder, CO 80309 (United States)
Publication Date:
OSTI Identifier:
20845987
Resource Type:
Journal Article
Resource Relation:
Journal Name: Annals of Physics (New York); Journal Volume: 322; Journal Issue: 1; Other Information: DOI: 10.1016/j.aop.2006.10.009; PII: S0003-4916(06)00239-9; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCURACY; ANISOTROPY; BOSE-EINSTEIN CONDENSATION; COOPER PAIRS; EXCITATION; FERMI GAS; FERMIONS; GASES; GROUND STATES; P WAVES; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; RESONANCE; S WAVES; SUPERCONDUCTORS; SUPERFLUIDITY; TOPOLOGY; VORTICES

Citation Formats

Gurarie, V., and Radzihovsky, L. Resonantly paired fermionic superfluids. United States: N. p., 2007. Web. doi:10.1016/j.aop.2006.10.009.
Gurarie, V., & Radzihovsky, L. Resonantly paired fermionic superfluids. United States. doi:10.1016/j.aop.2006.10.009.
Gurarie, V., and Radzihovsky, L. Mon . "Resonantly paired fermionic superfluids". United States. doi:10.1016/j.aop.2006.10.009.
@article{osti_20845987,
title = {Resonantly paired fermionic superfluids},
author = {Gurarie, V. and Radzihovsky, L.},
abstractNote = {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 p {sub x} + ip {sub y} 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.},
doi = {10.1016/j.aop.2006.10.009},
journal = {Annals of Physics (New York)},
number = 1,
volume = 322,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}