Thermodynamics and Non-Equilibrium Dynamics of Unitary Fermi Gases
报告人： Dr. Mark Jen-Hao Ku
Research Laboratory of Electronics (RLE)
Department of Physics,
Massachusetts Institute of Technology (MIT), USA
地点： 北京大学 理科2号楼2736报告厅
时间： 2014年9月2日（星期二），上午 10:00-11:00
Unitary Fermi gas - 2 components Fermi gas whose scattering length is much larger compared to inter-particle spacing - realizes a novel superfluid relevant to the study of high-Tc superconductor and neutron star. In this talk, I discuss the results on the thermodynamics and non-equilibrium dynamics of unitary Fermi gases obtained at MIT in the recent years. We realize unitary Fermi gas with lithium-6 near a broad Feshbach resonance. Accurate measurement of the thermodynamics reveals the superfluid lambda-transition in the heat capacity, and allows for the measurement of the ground state energy, also known as the Bertsh parameter. We have also developed a general technique to obtain thermodynamics directly from the observed column density of a gas. To study non-equilibrium dynamics, we investigate solitary waves in unitary Fermi gases, which is a novel probe of the superfluid. We demonstrate the first generation and observation of solitary waves in unitary Fermi gases. Tomography imaging reveals the solitary wave to be a solitonic vortex. We have measured the vortex precession period in the BEC-BCS crossover and developed a hydrodynamic theory to explain the precession period. We have also observed the cascade of planar soliton, vortex ring, and solitonic vortex in the unitary Fermi superfluid.