Polaron problems in ultracold atoms: Role of a fermi sea across different spatial dimensions and quantum fluctuations of a bose medium

Hiroyuki Tajima, Junichi Takahashi, Simeon I. Mistakidis, Eiji Nakano, Kei Iida

Research output: Contribution to journalArticlepeer-review

Abstract

The notion of a polaron, originally introduced in the context of electrons in ionic lattices, helps us to understand how a quantum impurity behaves when being immersed in and interacting with a many-body background. We discuss the impact of the impurities on the medium particles by considering feedback effects from polarons that can be realized in ultracold quantum gas experiments. In particular, we exemplify the modifications of the medium in the presence of either Fermi or Bose polarons. Regarding Fermi polarons we present a corresponding many-body diagrammatic approach operating at finite temperatures and discuss how mediated two-and three-body interactions are implemented within this framework. Utilizing this approach, we analyze the behavior of the spectral function of Fermi polarons at finite temperature by varying impurity-medium interactions as well as spatial dimensions from three to one. Interestingly, we reveal that the spectral function of the medium atoms could be a useful quantity for analyzing the transition/crossover from attractive polarons to molecules in three-dimensions. As for the Bose polaron, we showcase the depletion of the background Bose-Einstein condensate in the vicinity of the impurity atom. Such spatial modulations would be important for future investigations regarding the quantification of interpolaron correlations in Bose polaron problems.

Original languageEnglish
Article number18
JournalAtoms
Volume9
Issue number1
DOIs
Publication statusPublished - 2021 Mar

Keywords

  • Bose–Einstein condensate
  • Fermi degenerate gases
  • Impurity
  • Interpolaron correlations
  • Polaron
  • Quantum depletion
  • Spectroscopy of quasiparticles
  • Ultracold atoms

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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