Anomalous damping of excitations in a collisionless dipolar Bose gas
Stefan Natu, Ryan M. Wilson
We present a theory for the Landau damping of low energy quasi-particles in a collisionless, quasi- 2D dipolar Bose gas and produce expressions for the damping rate in uniform and non-uniform systems. In the homogeneous system, we find that the nature of the low energy dispersion in a dipolar Bose gas severely inhibits Landau damping of long wave-length excitations. For a gas with contact and dipolar interactions, the damping rate for phonons tends to decrease with increasing dipolar interactions, and for strong dipole-dipole interactions, phonons are virtually undamped over a broad range of temperature. By contrast, we find that the damping rate for roton-like excitations increases with increasing dipolar interactions.
Physical Review A (Atomic, Molecular and Optical Physics)