We develop a theory of damping of low-energy, collective excitations in a quasi-two-dimensional, homogenous, dipolar Bose gas at zero temperature, via processes whereby an excitation decays into two excitations with lower energy. We find that owing to the nature of the low-energy spectrum of a quasi-two-dimensional dipolar gas, such processes cannot occur unless the momentum of the incoming quasiparticle exceeds a critical value
kcrit. We find that as the dipolar interaction strength is increased, this critical value shifts to larger momenta. Our predictions can be directly verified in current experiments on dipolar Bose condensates using Bragg spectroscopy, and provide valuable insight into the quantum many-body physics of dipolar gases.
We examine the vortex formation and vortex lattices in a rotating dipolar Bose-Einstein condensate (BEC) with two- and three-body interactions. For this aim, we numerically solve the quasi two-dimensional, cubic-quintic Gross-Pitaevskii equation with nonlocal dipole-dipole nonlinearity. We find the critical rotation frequency for vortex formation in a pure dipolar BEC and also in a dipolar BEC with presence of both two- and three-body interactions. We also show the vortex lattices in a dipolar BEC with two- and three-body interactions for large rotation frequencies.
Abstract We investigate the effective interaction between two heavy impurities immersed in a quasi-two-dimensional dipolar Bose–Einstein condensate via a variation approach. We show that the mediated interaction is highly tunable via the contact and the dipole–dipole interactions between the background gas atoms. Interestingly, the mediated interaction potential may become an oscillating function of inter-impurity distance when roton excitation emerges under sufficiently strong dipolar interaction. Our system therefore provides an efficient way for tuning the mediated interaction between impurities.