[PAST EVENT] Charles T. Fancher, Physics - Oral Exam for the Ph.D. Degree
Abstract: Ultracold atom experiments use a gas of neutral atoms with temperatures less than 100 ?K above absolute zero and offer unmatched experimental control of quantum states and coherence, which has allowed ultracold atom-based measurements to be some of the most precise to date. While ultracold atom experiments can control almost all atomic degrees of freedom, spin-dependent trapping and spatial manipulation has remained difficult if not inaccessible. We are developing a method of spin-dependent trapping and spatial manipulation for ultracold neutral atoms using the AC Zeeman force produced by a microwave magnetic near-field gradient generated by an atom chip. We measure the AC Zeeman force on ultracold rubidium atoms by observing its effect on the motion of atoms in free-fall and on those confined in a trap. We have studied the force as a function of microwave frequency detuning from a hyperfine transition at 6.8 GHz at several magnetic field strengths and have observed its characteristic bipolar and resonant features predicted by two-level dressed atom theory. We find that the force is several times the strength of gravity in our setup, and that it can be targeted to a specific hyperfine transition while leaving other hyperfine states and transitions relatively unaffected. We find that our measurements are reasonably consistent with parameter-free theoretical predictions.
Bio: Charles Fancher was born and raised in beautiful Saginaw, Michigan. He attended the Saginaw Arts and Sciences Academy from 2003-2007 where he got hooked on physics in a sophomore year class taught by Steve Tack. His did his undergraduate education at Worcester Polytechnic Institute in Worcester, MA and received his B.S. in Physics in 2010. He started in the physics Ph.D. program at William & Mary in the fall of 2010 and joined the Aubin Cold Atoms lab in the summer of 2011. He has been working on demonstrating a practical AC Zeeman effect with a cold atom system.