Abstract:
Experimental evidence of the Higgs mode in strongly interacting superfluid Fermi gases had not been observed until recently [Behrle et al., Nat. Phys. 14, 781 (2018).]. Due to the coupling with other collective modes and quasiparticle excitations, generating stable Higgs-mode oscillations is challenging. We study how to excite long-lived Higgs-mode oscillations in a homogeneous superfluid Fermi gas in the BCS-BEC crossover. We find that the Higgs mode can be excited by time-periodically modulating the scattering length at an appropriate amplitude and frequency. However, even for a modulation frequency below twice the pairing-gap energy, quasiparticles are still excited through the generation of higher harmonics due to nonlinearity in the superfluid. More importantly, we find that persistent Higgs-mode oscillations with almost constant amplitude can be produced by removing particles at an appropriate momentum, and the oscillation amplitude can be controlled by the number of removed particles. Finally, we propose two ways to experimentally realize particle removal.
Biography:
Kui-Tian Xi is an Associate Professor at Nanjing University of Aeronautics and Astronautics (NUAA). He got his bachelor's degree and Ph.D. at the NUAA, then visited Professor Tim Byrnes' group at the National Institute of Informatics in Tokyo, Japan. He later worked as a postdoctoral research associate at the Institute of Physics, Chinese Academy of Sciences in 2015, then worked as a Research Scholar at Ohio State University until 2018. He later worked as an assistant researcher in the group of Professor Gentaro Watanabe at Zhejiang University until he joined NUAA in 2021. His current focus is quantum droplets and dipolar supersolids, superfluid Fermi gases and the application of machine learning in cold atoms.
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai