Wednesday, July 3, 2013

1307.0144 (M. A. Caracanhas et al.)

Tkachenko polarons in vortex lattices    [PDF]

M. A. Caracanhas, V. S. Bagnato, R. G. Pereira
We analyze the properties of impurities immersed in a vortex lattice formed by ultracold bosons in the mean field quantum Hall regime. Besides the effects of a periodic lattice potential, the impurity is dressed by collective modes with parabolic dispersion (Tkachenko modes). We derive the effective polaron model, which contains a marginal impurity-phonon interaction. The polaron spectral function exhibits a Lorentzian broadening for arbitrarily small wave vectors even at zero temperature, in contrast with the result for optical or acoustic phonons. The unusually strong damping of Tkachenko polarons could be detected experimentally using momentum-resolved spectroscopy.
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