"Phase patterned atom interferometry: measuring Tune Out in lithium," by Eric Copenhaver (UC Berkeley)

Friday, February 22, 2019 - 1:00pm to 2:00pm
AMO Seminars


One might naively think that any wavelength of light would induce an oscillating dipole moment in an atom, since light is an oscillating electric field and atoms comprise electric charges. At a tune-out wavelength, however, an atom is unresponsive. This occurs when AC Stark shifts from nearby transitions are equal and opposite, or more precisely when the atomic polarizability vanishes. Lithium is an interesting candidate for a precision measurement of a tune-out wavelength because its simple three-electron structure permits theorists to use high-accuracy methods that explicitly account for electron correlations. In this talk, I will describe a new atom interferometry method we develop to measure lithium's tune-out wavelength. A focused beam pulses through the laser-cooled cloud during the interferometer to imprint a spatially-varying phase gradient from the spatially-varying AC Stark shift. The interferometer turns the phase pattern into measurable population differences. Image processing reveals the feature and we determine the tune-out wavelength by identifying where the pattern vanishes. I will also discuss our ongoing evaluation of systematic effects.

Event Attachments: 
PAB 4-330