Fermi polaron revisited: polaron-molecule transition and coexistence

Abstract

We revisit the polaron-molecule transition in three-dimensional(3D) fermion systems using the well-established variational approach. The molecule is found to be intrinsically unstable against lowest-order particle-hole excitations, and it can only approximate the ground state of impurity system with finite total momentum in the strong coupling regime. The polaron-molecule transition can therefore be reinterpreted as a first-order transition between single impurity systems with different total momenta. Within certain interaction window near their transition, both states appear as local minima in the dispersion curve, indicating they can coexist in a realistic system. We have further confirmed the polaron-molecule coexistence in the presence of a finite impurity concentration and at low temperature, which directly leads to a smooth polaron-molecule transition as observed in recent experiments of 3D ultracold Fermi gases. Our results have provided an unambiguous physical picture for the competition and conversion between polaron and molecule, and also shed light on Fermi polaron properties in low dimensions.

5 pages, 5 figures; published version

References in corpus (18)

• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Attractive and repulsive Fermi polarons in two dimensions
• The Equation of State of a Low-Temperature Fermi Gas with Tunable Interactions
• Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series
• Repulsive Fermi polarons in a resonant mixture of ultracold ${}^6$Li atoms
• Normal state of a polarized Fermi gas at unitarity
• Homogeneous Atomic Fermi Gases
• Normal state of highly polarized Fermi gases: Full many-body treatment
• Excitation spectra and rf-response near the polaron-to-molecule transition from the functional renormalization group
• Trimers, molecules and polarons in imbalanced atomic Fermi gases
• Polaron-molecule transitions in a two-dimensional Fermi gas
• Highly polarized Fermi gases in two dimensions
• Polarons and Molecules in a Two-Dimensional Fermi Gas
• Decay of polarons and molecules in a strongly polarized Fermi gas
• Highly polarized Fermi gases: One-dimensional case
• Diagrammatic Monte Carlo study of quasi-two-dimensional Fermi-polarons
• Polarons and Molecules in a Fermi Gas with Orbital Feshbach Resonance
• A Non-Gaussian Variational Approach to Fermi Polarons in One- and Two-dimensional Lattices

Cited by in corpus (13)

• Non-Hermitian Squeezed Polarons
• Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium
• Thermodynamic signatures of the polaron-molecule transition in a Fermi gas
• Finite-range effects in the unitary Fermi polaron
• Nature of polaron-molecule transition in Fermi polarons
• Emergence of Crystalline Few-body Correlations in Mass-imbalanced Fermi Polarons
• An impurity immersed in a double Fermi Sea
• Competing few-body correlations in ultracold Fermi polarons
• Momentum-dependent quasiparticle properties of the Fermi polaron from the functional renormalization group
• Mass-gap description of heavy impurities in Fermi gases
• Efficient variational approach to the Fermi polaron problem in two dimensions, both in and out of equilibrium
• The normal state of attractive Fermi gases from coupled-cluster theory
• Functional-renormalization-group approach to strongly coupled Bose-Fermi mixtures in two dimensions