Emulating Layered Materials with Ultra-cold Fermi Gases

We create a new paradigm for emulating quasi-two-dimensional materials, by confining an ultra-cold Fermi gas in an infrared CO2 laser standing-wave, which produces periodic pancake-shaped potential wells, separated by 5.3 m. We load an ultra-cold mixture of N1 = 800 spin ½-up and N2 < N1 spin ½-down 6Li atoms into each well and image the individual cloud profiles to study the thermodynamics of this system as a function of interaction strength and spin imbalance N2/N1. This array of two-dimensional mesoscopic clouds offers unprecedented opportunities to test predictions that cross interdisciplinary boundaries, such as enhanced superfluid transition temperatures in spin-imbalanced quasi-2D superconductors and phase-separation in nuclear matter.

Professor Thomas is exploring the physics of an optically trapped degenerate Fermi gas. The group pioneered the development of ultrastable all-optical traps for neutral atoms in 1999, achieving trap lifetimes of more than 400 seconds, comparable to the best magnetic traps. The group has developed methods for direct evaporative cooling of neutral atoms in optical traps, enabling the first all-optical production of a degenerate Fermi gas in 2001. The trapped gas comprises a degenerate 50-50 mixture of spin-up and spin-down fermionic lithium-6 atoms, which exhibits a collisional (Feshbach) resonance in a bias magnetic field. In 2002, the Duke group was the first to produce and study a strongly interacting degenerate Fermi gas. This system exhibits universal behavior and is a paradigm for testing nonperturbative many-body calculational methods in disciplines from nuclear matter to high temperature superconductors. In 2004, the Duke group was the first to observe evidence for high temperature superfluid hydrodynamics in a strongly interacting Fermi gas. Ongoing experiments include studies of the thermodynamics and transport properties of this unique quantum system.