Dark solitons dynamics and snake instability in superfluid Fermi gases trapped by an anisotropic harmonic potential

Abstract

We present an investigation of generation, dynamics and stability of dark solitons in anisotropic Fermi gases for a range of particle numbers and trap aspect ratios within the framework of the order-parameter equation. We calculate the periods of dark solitons oscillating in a trap, and find a good agreement with the results based on the Bogoliubov-de Gennes equations. By studying the stability of initially off-center dark solitons under various tight transverse confinements in the unitarity limit, we not only give the criterion of dynamical stability, but also find that the soliton and a hybrid of solitons and vortex rings can be characterized by different oscillation period. The stability criterion is not fulfilled by the parameters of the recent experiment [Nature {\bf 499}, 426 (2013)]. Therefore, instead of a very slow oscillation as observed experimentally, we find that the created dark soliton undergoes a transverse snake instability with collapsing into vortex rings, which propagate in soliton-like manner with a nearly two times larger period.

19 pages, 7 figures

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• Nonlinear Schrödinger equation for a superfluid Fermi gas from BCS to Bose crossover
• DC Josephson Effect with Fermi gases in the Bose-Einstein regime
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• Dark solitons as quasiparticles in trapped condensates
• Snake instability of dark solitons in fermionic superfluids
• Density Functional Theory for non-relativistic Fermions in the Unitarity Limit
• Expansion of a Fermi Cloud in the BCS-BEC Crossover
• Dark matter-wave solitons in the dimensionality crossover
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• Critical Rotational Frequency for Superfluid Fermionic Gases across a Feshbach Resonance
• DC and AC Josephson effects with superfluid Fermi atoms across a Feshbach resonance
• Bell Soliton in Ultra-cold Atomic Fermi Gas

Cited by in corpus (14)

• Motion of a Solitonic Vortex in the BEC-BCS Crossover
• Fortran and C programs for the time-dependent dipolar Gross-Pitaevskii equation in an anisotropic trap
• From Planar Solitons to Vortex Rings and Lines: Cascade of Solitonic Excitations in a Superfluid Fermi Gas
• Chladni solitons and the onset of the snaking instability for dark solitons in confined superfluids
• Life Cycle of Superfluid Vortices and Quantum Turbulence in the Unitary Fermi Gas
• Finite temperature effective field theory for dark solitons in superfluid Fermi gases
• Collective modes of a soliton train in a Fermi superfluid
• Weak-coupling to unitarity crossover in Bose-Fermi mixtures: Mixing-demixing and spontaneous symmetry breaking in trapped systems
• Generic transverse stability of kink structures in atomic and optical nonlinear media with competing attractive and repulsive interactions
• Protocol to engineer Fulde-Ferrell-Larkin-Ovchinnikov states in a cold Fermi gas
• Transport of Spin and Mass at Normal-Superfluid Interfaces in the Unitary Fermi Gas
• Perturbation-induced defects in trapped superfluids exhibit generic behavior
• Vortex-lattice structures in rotating Bose-Fermi superfluid mixtures
• Dynamics of a solitonic vortex in an anisotropically trapped superfluid