Manifestations of the roton mode in dipolar Bose-Einstein condensates.

Manifestations of the Roton in Dipolar Bose-Einstein Condensates

Effective dipole-dipole interactions in multilayered dipolar Bose-Einstein condensates

We propose a two-dimensional model for a multilayer stack of dipolar Bose-Einstein condensates formed by a strong optical lattice. We derive effective intraand interlayer dipole-dipole interaction potentials and provide simple analytical approximations for a given number of lattice sites at arbitrary polarization. We find that the interlayer dipole-dipole interaction changes the transverse aspe...

Geometric stability spectra of dipolar Bose gases in tunable optical lattices

We examine the stability of quasi-two-dimensional dipolar Bose-Einstein condensates in the presence of weak optical lattices of various geometries. We find that when the condensate possesses a roton-maxon quasiparticle dispersion, the conditions for stability exhibit a strong dependence both on the lattice geometry and the polarization tilt. This results in rich structures in the system’s stabi...

Angular collapse of dipolar Bose-Einstein condensates

We explore the structure and dynamics of dipolar Bose-Einstein condensates DBECs near their threshold for instability. Near this threshold a DBEC may exhibit nontrivial biconcave density distributions, which are associated with instability against collapse into “angular roton” modes. Here we discuss experimental signatures of these features. In the first, we infer local collapse of the DBEC fro...

Emergent structure in a dipolar Bose gas in a one-dimensional lattice

We consider an ultracold dipolar Bose gas in a one-dimensional lattice. For a sufficiently large lattice recoil energy, such a system becomes a series of nonoverlapping Bose-Einstein condensates that interact via the long-range dipole-dipole interaction (ddi). We model this system via a coupled set of nonlocal Gross-Pitaevskii equations (GPEs) for lattices of both infinite and finite extent. We...