Shell-shaped BECs: collective modes and other properties
Recent experimental work with "bubble" traps opens up a path to observe BECs in a new geometry: confined to the surface of a sphere. Bubble traps in principle enable a trapped BEC's shape to be continuously tuned between a thin spherical shell and an ordinary harmonically-confined sphere. First, I'll present theoretical and numerical work detailing the collective modes of a bubble-trapped BEC and their evolution between the 2d shell limit and the well-understood 3d spherical limit. We'll see that the frequencies of the collective modes are non-monotonic and produce a signature of the hollowing out that occurs as the sphere becomes a shell. I'll then turn to recent work on achieving a bubble-trapped BEC in the Cold Atom Laboratory (CAL) on the International Space Station. We'll see that within the confines of the current CAL chip, we lose spherical symmetry, but the microgravity environment should enable us to produce a boundaryless simply-connected 2d condensate.