We propose to investigate the instability of superfluid flow in a dilute Bose-Einstein condensate with repulsive interactions. Landau proposed that the primary mechanism for superfluid flow instability is the excitation of quasiparticles.
While this is t he traditionally accepted explanation, the critical velocity, i.e. the velocity at which the superfluid flow becomes unstable, that Landau predicted based on quasiparticle excitation is generally known to be significantly higher than the experimentally ascertained critical velocity. Preliminary calculations show that using the breakdown of thermodynamic equilibrium as the primary mechanism for instability leads to a theorized critical velocity that is much lower than the Landau critical velocity.
We thus plan to tackle the problem of superfluid flow instability by developing a kinetic theory consistent with the new critical velocity arising from the breakdown of the thermodynamic equilibrium, using this kinetic theory to develop a new two-fluid model, numerically simulating this model, and working closely with experimenters to verify our results.
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