Dan Stamper-Kurn
University of California, Berkeley
Friday, October 12, 2007
4:00 pm in SPL 57
Thermal and quantum phases of a spin-1 Bose gas
Abstract: In the regime of quantum degeneracy, obtained experimentally at temperatures well below one microkelvin, a gas of spin-1 rubidium atoms is predicted to become simultaneously superfluid and magnetically ordered. We have studied such a gas using a magnetization sensitive method to measure the complete vector magnetization in situ. I will present three main findings from our work. First, we have found that optically trapped, quantum degenerate spin-1 atoms are particularly suited for use as a sensing medium for inhomogeneous magnetic fields, and have demonstrated a spatially resolving magnetometer with sensitivity rivalling that of today's best field sensors. Second, we have identified a quantum phase transition in these gases between a paramagnetic and a ferromagnetic phase, and have studied the dynamics of a gas that is suddenly quenched across this transition. Third, we have ascertained that magnetic dipole interactions are strongly relevant to the properties of a spin-1 rubidium quantum fluid, and have begun probing the consequence of these interactions for its equilibrium phase diagram.
[RETURN]