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Thermodynamics and Non-Equilibrium Dynamics of Unitary Fermi

时间:2014-09-02 作者: 来源:

学术报告

 

报告题目

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: 201492日(星期二),上午 10:00-11:00



 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.