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Center for Nonlinear Studies |
Quantum fluids often exhibit remarkable properties which can make them useful for constructing sensors and other devices, such as SQUID magnetometers and superfluid helium gyroscopes. I will describe recent experiments conducted at the Joint Quantum Institute with a dilute gas of ultracold sodium atoms in a ring-shaped geometry. In these experiments we were able to control the (quantized) circulation state of a toroidal atomic Bose-Einstein condensate with a rotating "weak link" created by a repulsive optical dipole potential. This system is directly analogous to a superconducting loop in an external magnetic field, where the loop is interrupted by a weak link with a dynamically tunable current-phase relation. We have observed phenomena such as discrete phase slips between circulation states, and hysteresis in the total "rotational flux" as a function of the applied "rotational flux". I will also discuss prospects for using SQUID-like atom “circuits” for rotation sensing, and as a means for investigating the exotic properties of macroscopic quantum systems.
Host: Changhyun Rhu, P-21, cryu@lanl.gov