The Ultracold Atoms and Plasmas Group at Rice University, under the direction of Professor Thomas C. Killian, is accepting applications for a post-doctoral research position in experimental atomic physics. The general research topics of the group are ultracold neutral plasmas, cold collisions, high resolution spectroscopy, and quantum gases. Applicants should have a Ph.D in atomic physics or closely related field, and have experience with ultracold atoms or ions. Rice University is an equal opportunity/affirmative action employer.

Applications, consisting of a cover letter, CV, statement of research interests and goals, and three letters of recommendation, should be sent to:

Thomas C. Killian
Rice University
Dept. of Physics and Astronomy, MS-61
6100 Main St.
Houston, TX 77005

For more information, contact Thomas C. Killian at killian@rice.edu.

The Ultracold Atoms and Plasmas Group

The Ultracold Atoms and Plasmas Group studies ultracold neutral plasmas and ultracold atomic gases. Both experiments start with laser-cooled and trapped neutral strontium. Laser cooling is a powerful technique for producing and trapping atoms at temperatures as low as one millionth of a degree above absolute zero. Under these exotic conditions, matter behaves in fundamentally different ways, and the exploration of this regime teaches us about the basic laws of nature and lays the foundation for powerful new technological advances, such as ultra-precise clocks or quantum computers.

Ultracold Neutral Plasmas

The group's first PRL described absorption imaging of a strontium plasma. This technique is the starting point for numerous experiments on equilibration and dynamics of ultracold plasmas.

In a paper recently accepted at PRL, we reported the first experimental observation of kinetic energy oscillations in equilibrating strongly-coupled plasmas. This phenomenon has been studied since the 1990's with computer simulations of plasmas produced by irradiation of solids and clusters with fast-pulsed lasers, but this is the first experimental observation. Kinetic energy oscillations are manifestations of spatial correlations that arise from strong coupling. Ions oscillate around the local potential energy minima that are formed as particles minimize their interaction energy by maximizing the distance from their neighbors. The primary motivation for these experiments is to understand how plasmas behave in this exotic regime. This may shed light on other systems in which strong-coupling plays a role, such as white dwarf stars, inertial confinement fusion systems, and quark-gluon plasmas.

Future directions are to develop laser cooling and trapping of the ions in the plasma. Electrons would be confined by Coulomb attraction. This would be an entirely new method of plasma confinement and should lead to drastically lower temperatures. We also plan to examine light scattering from the ions as a means to directly probe spatial correlations.

Figure A. Absorption imaging of an ultracold neutral plasma. B. Kinetic energy evolution of ions for different regions in an ultracold neutral plasma.

Laser Cooled Neutral Strontium

Alkaline-earth atoms have become the focus of intense experimental and theoretical activity in recent years. Extremely narrow optical transitions in these atoms make them ideal for the next generation of optical frequency standards, and enable laser cooling to within an order of magnitude of quantum degeneracy. Cold collisions in these systems are also of fundamental interest because the ground state is closed-shelled, and lacks hyperfine structure, making these atoms ideal for testing cold collision theory. Atoms in excited metastable levels interact through strong, long-range dipole-dipole and quadropole-quadrupole forces that should lead to novel properties for quantum degenerate gases.

Strontium laser cooling is the most advanced of all the alkaline-earth species. In the Killian lab, we have studied magnetic trapping of metastable levels, and have performed extensive photoassociative spectroscopy of the two primary bosonic isotopes. The next goal is to put strontium in an optical dipole trap and evaporate to quantum degeneracy. The excellent performance of our laser cooling apparatus puts us in a great position for this pursuit. The long term plan is to study high resolution spectroscopy of the condensate and the behavior of degenerate gases in lattices.

Figure: Photoassociative spectroscopy of 88Sr at very long range.