Quantum Transport in Strongly Interacting Fermi Gases

This program experimentally studies an optically-trapped, strongly interacting Fermi gas of Li(6) atoms as a model of universal quantum transport. This system offers unprecedented opportunities to test theoretical techniques that cross interdisciplinary boundaries, from condensed matter to nuclear matter. Measurements in ultracold Fermi gases now unite the coldest matter in the universe to the hottest matter, a quark-gluon plasma produced in gold ion collisions, which is comparable to the state of matter that existed microseconds after the Big Bang. Remarkably, both systems are found to be nearly 'perfect' fluids, in the context of a recent conjecture derived using string theory methods, with a similar ratio of viscosity to entropy density, despite a difference in temperature of 19 orders of magnitude and a difference in density of 25 orders of magnitude.

The proposed tabletop experiments impact theories of strong interactions in intellectual disciplines well outside atomic physics, including materials science and condensed matter physics (superconductivity), nuclear physics (nuclear matter, quark-gluon plasma), high-energy physics (effective theories of strong interactions), and astrophysics (compact stellar objects). The proposed research may have practical impact in helping to determine whether it is possible to create super-high temperature nearly perfect conductors based on normal fluids, which would operate far above room temperature--materials that would enable energy-saving power lines and magnetically levitated trains. For this reason, the proposed program fits very well into national initiatives on energy and materials science.