Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium

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.

39 pages, 9 figures

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Cited by in corpus (6)

• Polarons and bipolarons in a two-dimensional square lattice
• Quantum-limited thermometry of a Fermi gas with a charged spin particle
• Counterflow dynamics of two correlated impurities immersed in a bosonic gas
• Complex Langevin study for polarons in an attractively interacting one-dimensional two-component Fermi gas
• Brueckner $G$-matrix approach to two-dimensional Fermi gases with the finite-range attractive interaction
• Entangling lattice-trapped bosons with a free impurity: impact on stationary and dynamical properties