##
Defect structures and topological interface engineering in a spinor
Bose-Einstein condensate

### Magnus Borgh

**Wednesday, 24 October 2012, 13:30**

Matfys library

**Abstract**:

In a BEC where the constituent atoms retain their spin degree of
freedom, spin rotations combine with the condensate phase to yield a
large manifold of physically distinguishable states. This leads to a
set of topologically distinct phases with a rich phenomenology of
topological defects such as vortices. Here I will give an
introduction to topological defects in a spin-1 BEC and show how stable
vortex structures can be understood from a hierarchy
of characteristic length scales. Boundaries between topologically
distinct regions are important for example in early-universe cosmology
and superfluid He-3. I will propose a scheme for how such a
topological interface could be created in a spinor BEC, and show
examples of interface-crossing defect states, highlighting how
ultracold atomic gases could be used as quantum emulators of for
example cosmic topological defects.