Topological transitions for lattice bosons in a magnetic field

Sebastian Huber

Department of Condensed Matter Physics, The Weizmann Institute of Science, Rohovot, Israel

In a moving superfluid a force acts on a vortex similar to the Magnus force acting on a spinning football. In the absence of disorder, the resulting vortex velocity has to be parallel to the motion of the superfluid. The direction, with or against the flow, and the speed of the vortex is only fixed in a Galilean invariant system, however. Here, we discuss a general setup of interacting lattice- bosons and map out a phase diagram for the behavior of the vortex. We find that the strongly interacting superfluid is characterized by a topological index. Our findings have a clear experimental signature and we show how it gives rise to a unambiguous definition of what a bosonic "hole condensate" is.