Ring Bose-Einstein condensates: choose your own adventure
In this talk, I will present some recent results from the rings lab at NIST. Most of our experiments involve ring-shaped Bose-Einstein condensates. These condensates are superfluids and are able to support quantized, persistent flows around the ring. A rotating perturbation, or weak link, drives transitions between these different quantized current states. To keep this talk to 30 minutes, it will be an audience-chosen adventure, with three possible choices:
1. Temperature dependence of the transitions between persistent current states. We find that the rotation rate needed to drive transitions between current states depends strongly on the temperature of the condensate. We also see behavior that might be analogous to macroscopic quantum tunneling.
2. A minimally-destructive measurement technique for detecting the persistent current state of the ring.
3. Resonant phonon wavepackets. In a set of recent experiments, we created phonon wavepackets that travel around the ring. If we create wavepackets at a frequency commensurate with their orbital frequency, the efficient energy transfer to the condensate results in enhanced atom loss.