Affiliation:
1. Pitaevskii Center on Bose-Einstein Condensation
2. University of Trento
Abstract
We investigate the various physical mechanisms that underlie the
dynamical instability of a quantized vortex array at the interface
between two counter-propagating superflows in a two-dimensional
Bose–Einstein condensate. Instabilities of markedly different nature are
found to dominate in different flow velocity regimes. For moderate
velocities where the two flows are subsonic, the vortex lattice displays
a quantized version of the hydrodynamic Kelvin–Helmholtz instability
(KHI), with the vortices rolling up and co-rotating. For supersonic flow
velocities, the oscillation involved in the KHI can resonantly couple to
acoustic excitations propagating away in the bulk fluid on both sides.
This makes the KHI rate to be effectively suppressed and other
mechanisms to dominate: For finite and relatively small systems along
the transverse direction, the instability involves a repeated
superradiant scattering of sound waves off the vortex lattice; for
transversally unbound systems, a radiative instability dominates,
leading to the simultaneous growth of a localized wave along the vortex
lattice and of acoustic excitations propagating away in the bulk.
Finally, for slow velocities, where the KHI rate is intrinsically slow,
another instability associated to the rigid lateral displacement of the
vortex lattice due to the vicinity of the system’s boundary is found to
dominate.
Funder
Horizon 2020
Provincia Autonoma di Trento
Subject
General Physics and Astronomy
Cited by
3 articles.
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