NC State University

Physics Department



Our program broadly explores Fermi gases with magnetically tunable ineractions near a collisional (Feshbach) resonance, utilizing stable optical traps and all-optical cooling methods. Our investigation of laser-noise-induced heating in optical traps (Savard 1997) showed that intensity noise, at twice the harmonic oscillation frequency of atoms in the trap, caused parametric heating and subsequent atom loss, limiting the trap lifetime to less than 10 seconds. Using an ultrastable CO2 laser, this heating time was increased to 23,000 seconds. Further, the photon scattering rate was reduced to 2 photons per hour per atom, so that the trap lifetime was limited by background gas collisions at <10-11 Torr to more than 400 seconds.

Using these techniques, our group made the first studies of hydrodynamics in a strongly interacting Fermi gas, with the observation of elliptic flow (2002) and the obtained the first evidence for superfluidity in (2004), based on studies of collective modes. Our group developed the first model-independent methods for measuring the global energy and entropy of the trapped gas from images of the cloud (2007,2009). We also made the first measurements of hydrodynamic transport coefficients in our studies of shear viscosity and perfect fluidity (2011,2012).