Physics & Astronomy Colloquium

3:30 PM, Friday, March 21, 2008
Room 155, Chem-Phys Building

Dr. Michael Romalis
Department of Physics
Princeton University

"Precision measurements with alkali-metal atoms''

Alkali-metal atoms with well-controlled degrees of freedom provide an ideal system for high sensitivity measurements. I will discuss recent advances in precision measurements using spin-polarized alkali-metal atoms, focusing on their use for detection of weak magnetic fields and searches for physics beyond the Standard Model. The sensitivity of these measurements depends crucially on the electron spin coherence time which is usually limited by atomic collisions. Careful analysis of the collision properties allows one to choose operating regimes where the spin coherence time is increased by several orders of magnitude. With these improvements atomic magnetometers are now surpassing cryogenic SQUID magnetometers which have long been considered most sensitive magnetic field sensors. Higher sensitivity and absence of cryogens open new applications for atomic magnetometers, including detection of nuclear magnetic resonance signals and magnetic fields generated by the brain. For fundamental physics tests, we developed a noble gas- alkali-metal co-magnetometer with two spin species occupying the same volume, which allows one to cancel ordinary magnetic fields while retaining sensitivity to exotic effects beyond the Standard Model. Such arrangement is being used to search for spin-dependent forces, Lorentz-violating spin couplings, and a CP-violating permanent electric dipole moment.

Refreshments will be served in CP 179 at 3:15 PM