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

Journal Article · Wed Aug 15 04:00:00 EDT 2007 · Annals of Physics (New York)

DOI:https://doi.org/10.1016/j.aop.2006.09.009· OSTI ID:20976782

Sheehy, Daniel E ^[1]; Radzihovsky, Leo ^[1]

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1. Department of Physics, University of Colorado, Boulder, CO 80309 (United States)

We study resonantly-paired s-wave superfluidity in a degenerate gas of two species (hyperfine states labeled by {up_arrow}, {down_arrow}) of fermionic atoms when the numbers N {sub {up_arrow}} and N {sub {down_arrow}} 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 {delta}N {identical_to} N {sub {up_arrow}} - N {sub {down_arrow}}. Our findings are summarized by a 'polarization' ({delta}N) versus Feshbach-resonance detuning ({delta}) 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.

• OSTI ID: 20976782
• Journal Information: Annals of Physics (New York), Journal Name: Annals of Physics (New York) Journal Issue: 8 Vol. 322; ISSN 0003-4916; ISSN APNYA6
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BCS THEORY
BOSE-EINSTEIN CONDENSATION
COOPER PAIRS
FERMI GAS
FERMIONS
PERIODICITY
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
POLARIZATION
S WAVES
SUPERFLUIDITY