Research Team Members

Juan Pino

Rob Wild
Zachary Newman

Research

The first dilute gas Bose-Einstein condensate (BEC) was made at JILA in 1995. The gas BEC is a superfluid and is related to another superfluid, which is liquid He.  For years scientists have studied superfluid liquid He, trying to understand its properties, but the fact that this state of matter occurred in a strongly interacting liquid made this inherently difficult.

Rob Wild and Juan Pino

One of the things that made the 1995 discovery so exciting was that we now had a much simpler system in which to understand Bose-Einstein condensation and superfluidity. Our BEC occurs in an ultracold, low density gas. In superfluid He, one has a liquid, where the interactions between particles are inherently stronger than that of a gas, and this makes the system challenging from a theoretical perspective.

Our goal is to bridge the gap between these two superfluid systems. In our experiments we make Bose-Einstein condensates using a gas of ⁸⁵Rb atoms. We choose ⁸⁵Rb because there exists a magnetic-field tunable Fano-Feshbach resonance that one can use to tune the interactions between atoms from very weak to very strong. We probe our system using two-photon Bragg spectroscopy and are interested in studying such properties as the dispersion relation of a strongly interacting BEC as well as searching for rotons, which have been observed in liquid He, but not in the dilute gas superfluids.