Laser Cooled Neutral Plasmas: A Laboratory for the Study of Strongly Coupled Systems*

Strong coupling arises when interaction energies are comparable to, or exceed, kinetic energies, and this occurs in diverse systems such as white dwarf stars, strongly correlated electron systems, and cold quantum gases. Ultracold neutral plasmas (UNPs), generated by photoionization of a laser-cooled gas, are a powerful platform for studying the physics of strongly coupled Yukawa plasmas. I will briefly describe experimental studies of self-diffusion and thermal equilibration, and describe the role of strong coupling in these phenomena. I will also present results from the first application of laser-cooling to a neutral plasma.  Through laser-cooling we have created plasmas with ion temperatures as low as 50 mK and achieved a factor of 4 enhancement in the coupling strength to \Gamma=11, allowing for experimental benchmarking of new models and molecular dynamics simulations of transport across a range of coupling strength.