Propagation of sound and supersonic bright solitons in superfluid Fermi gases in BCS-BEC crossover

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.81.014528· OSTI ID:21366649

Wen, Wen ^[1]; Shunqing, Shen ^[2]; Guoxiang, Huang ^[3]

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1. Department of Physics, East China Normal University, Shanghai 200062 (China)
2. Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong)
3. State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China)

We investigate the linear and nonlinear sound propagations in a cigar-shaped superfluid Fermi gas with a large particle number. We first solve analytically the eigenvalue problem of linear collective excitations and provide explicit expressions of all eigenvalues and eigenfunctions, which are valid for all superfluid regimes in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensation (BCS-BEC) crossover. The linear sound speed obtained agrees well with that of a recent experimental measurement. We then consider a weak nonlinear excitation and show that the time evolution of the excitation obeys a Korteweg de Vries equation. Different from the result obtained in quasi-one-dimensional case studied previously, where subsonic dark solitons are obtained via the balance between quantum pressure and nonlinear effect, we demonstrate that bright solitons with supersonic propagating velocity can be generated in the present three-dimensional system through the balance between a waveguidelike dispersion and the interparticle interaction. The supersonic bright solitons obtained display different physical properties in different superfluid regimes and hence can be used to characterize superfluid features of the BCS-BEC crossover.

• OSTI ID: 21366649
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 81, Issue 1; Other Information: DOI: 10.1103/PhysRevB.81.014528; (c) 2010 The American Physical Society; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
BOSE-EINSTEIN CONDENSATION
COLLECTIVE EXCITATIONS
DISPERSIONS
EIGENFUNCTIONS
EIGENVALUES
FERMI GAS
INTERACTIONS
KORTEWEG-DE VRIES EQUATION
ONE-DIMENSIONAL CALCULATIONS
PHYSICAL PROPERTIES
SOLITONS
SOUND WAVES
SUPERFLUIDITY
THREE-DIMENSIONAL CALCULATIONS
VELOCITY
WAVE PROPAGATION
DIFFERENTIAL EQUATIONS
ENERGY-LEVEL TRANSITIONS
EQUATIONS
EXCITATION
FUNCTIONS
PARTIAL DIFFERENTIAL EQUATIONS
QUASI PARTICLES