Physics @ Berkeley
Events in Physics
Title: Thermal And Quantum Phases Of A Spin-1 Bose Gas    (Colloquia)
Start Date: 10/29/2007
Time: 4:30 pm
Location: 1 LeConte
Speaker: Dan Stamper-Kurn
Affiliation: UC Berkeley
Contact Person: Nathan Proctor   (510) 642-3034

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.  I also hope to present brief advertisements of other activities in our group.