ATOMIC PHYSICS SEMINAR

Edward Somerville Shuman
University of Virginia

Tuesday, February 5, 2008
2:00 pm in SPL 52

Spontaneous Ionization in a Frozen Rydberg Gas

Abstract: In cold Rydberg atom samples the dipole-dipole interaction can lead to many interesting dynamic processes. In particular it can lead to atomic motion, spontaneous ionization, and even plasma formation. Here we present measurements of spontaneous ionization in a dense gas of 300 μK ⁸⁵Rb atoms of n ~ 50. At densities of ~ 10¹⁰ cm^-3 ionization occurs on a 100 ns time scale, far too fast to be explained by the motion of the atoms or photoionization by 300 μK blackbody radiation. Rapid ionization is accompanied by spectral broadening and by the emergence of new features, which we attribute to multiple atom absorptions. We attribute the rapid ionization to a sequence of near resonant dipole-dipole transitions through virtual states in this intrinsically many-body system, culminating in the ionization of some of the atoms.