报告题目：Thermodynamics and Non-Equilibrium Dynamics of Unitary Fermi Gases

报 告 人：Mark Jen-Hao Ku，Research Laboratory of Electronics (RLE)，Department of Physics, Massachusetts Institute of Technology (MIT), USA

报告时间：2014年9月3日10:00

报告地点：物理系三楼报告厅

报告摘要：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.