Polarons and Molecules in a Two-Dimensional Fermi Gas

Abstract

We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp transition to a dimer state with increasing interspecies attraction, we show that the polaron ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both ansätze give inaccurate results.

5 pages, 2 figures, minor changes

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Cited by in corpus (17)

• Attractive and repulsive Fermi polarons in two dimensions
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Polaron-molecule transitions in a two-dimensional Fermi gas
• Highly polarized Fermi gases in two dimensions
• Spin-Imbalanced Quasi-Two-Dimensional Fermi Gases
• Electron-exciton interactions in the exciton-polaron problem
• Observation of coherent multiorbital polarons in a two-dimensional Fermi gas
• Molecule and polaron in a highly polarized two-dimensional Fermi gas with spin-orbit coupling
• Diagrammatic Monte Carlo study of quasi-two-dimensional Fermi-polarons
• Three-component Ultracold Fermi Gases with Spin-Orbit Coupling
• Two-dimensional short-range interacting attractive and repulsive Fermi gases at zero temperature
• Thermodynamic signatures of the polaron-molecule transition in a Fermi gas
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases
• Polaron in a $p+ip$ Fermi topological superfluid
• Highly polarized one-dimensional Fermi gases near a narrow $p-$wave resonance
• Brueckner $G$-matrix approach to two-dimensional Fermi gases with the finite-range attractive interaction
• One-Dimensional Quantum Systems - From Few to Many Particles