学术报告 Higgs/amplitude mode and non-equilibrium dynamics of strongly interacting Fermi gases
【报告题目】 Higgs/amplitude mode and non-equilibrium dynamics of strongly interacting Fermi gases
【报 告 人】 Dr. Kuiyi Gao
Physikalisches Institut, University of Bonn
【时 间】 2018-01-03 星期三 16:00
【地 点】 北园物理楼106
Ultra-cold Fermi gases with tunable interactions have been widely used to investigate the BEC-BCS crossover in the last decade and superfluidity of Fermi gases with strong interaction have shown a variety of rich physics. Excitations and non-equilibrium dynamics related to pairing in strongly interacting atomic Fermi gases was proposed for studying excitations and pairing dynamics in superconductivity, however, experimental realization has been hindered by the difficulty of performing fast enough perturbations to the system.
In this talk, I will show our efforts in exploring Higgs/amplitude mode and non-equilibrium dynamics of strongly interacting Fermi gases of 6Li atoms. Firstly, I will show our recent observation of the Higgs mode in a strongly-interacting superfluid Fermi gas. By inducing a periodic modulation of the amplitude of the superconducting order parameter ∆ with RF field, we observe an excitation resonance at frequency 2∆/h. For strong coupling, the peak width broadens and eventually the mode disappears when the Cooper pairs turn into tightly bound dimers signalling the eventual instability of the Higgs mode. Secondly, I will discuss our experiment of the non-equilibrium dynamics of strongly interacting Fermi gases following rapid interaction quenches. With a fast population transfer, the interaction cross the Feshbach resonances between the different spin components is rapidly quenched, which induces non-equilibrium dynamics beyond prediction of BCS theory.
Dr. Kuiyi Gao received his BS (2006) from Wuhan University and Ph.D from Institute of Physics, Chinese Academy of Sciences (2014). He has been working as a postdoc fellow in M. Koehl group, Physikalisches Institut, University of Bonn (Germany). He built a new 23Na-6Li experimental setup in Bonn and his current research is focusing on ultra-cold Fermi gases experiment, especially on excitation and non-equilibrium dynamics of strongly interacting Fermionic superfluid under external driving.
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