Dynamical Density Fluctuation of Superfluids near Critical Velocities

Abstract

We propose a stability criterion of superfluids in condensed Bose-Einstein systems, which incorporates the spectral function or the autocorrelation function of the local density. Within the Gross-Pitaevskii-Bogoliubov theory, we demonstrate the validity of our criterion for the soliton-emission instability, with use of explicit forms of zero modes of the Bogoliubov equation and a dynamical scaling near the saddle-node bifurcation. We also show that the criterion is applicable to the Landau phonon instability and the Landau roton instability within the single-mode approximation.

4 pages, 1figure

References in corpus (3)

• Stationary and non-stationary fluid flow of a Bose-Einstein condensate through a penetrable barrier
• Absence of Anomalous Tunneling of Bogoliubov Excitations for Arbitrary Potential Barrier under the Critical Condensate Current
• Critical velocities in superfluids and the nucleation of vortices

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• Current production in ring condensates with a weak link
• Nonequilibrium steady states of Bose-Einstein condensates with a local particle loss in double potential barriers
• Excitation Transport through a Domain Wall in a Bose-Einstein Condensate
• Two-dimensional Schrödinger symmetry and three-dimensional breathers and Kelvin-ripple complexes as quasi-massive-Nambu-Goldstone modes
• Newton's equation of motion with quadratic drag force and Toda's potential as a solvable one
• Stability Criterion for Superfluidity based on the Density Spectral Function
• Creation of excitations from a uniform impurity motion in the condensate
• Bogoliubov Theory for a Superfluid Bose Gas Flowing in a Random Potential: Stability and Critical Velocity
• Holographic superfluid flows with a localized repulsive potential