Highly polarized Fermi gases in two dimensions

Abstract

We investigate the highly polarized limit of a two-dimensional (2D) Fermi gas, where we effectively have a single spin-down impurity atom immersed in a spin-up Fermi sea. By constructing variational wave functions for the impurity, we map out the ground state phase diagram as a function of mass ratio M/m and interaction strength. In particular, we determine when it is favorable for the dressed impurity (polaron) to bind particles from the Fermi sea to form a dimer, trimer or even larger clusters. Similarly to 3D, we find that the Fermi sea favors the trimer state so that it exists for M/m less than the critical mass ratio for trimer formation in the vacuum. We also find a region where dimers have finite momentum in the ground state, a scenario which corresponds to the Fulde-Ferrell-Larkin-Ovchinnikov superfluid state in the limit of large spin imbalance. For equal masses (M=m), we compute rigorous bounds on the polaron-dimer transition, and we show that the polaron energy and residue is well captured by the variational approach, with the former quantity being in good agreement with experiment. When there is a finite density of impurities, we find that this polaron-dimer transition is preempted by a first-order superfluid-normal transition at zero temperature, but it remains an open question what happens at finite temperature.

14 pages, 9 figures

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• Spin-Imbalanced Quasi-Two-Dimensional Fermi Gases
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• Diagrammatic Monte Carlo study of mass-imbalanced Fermi-polaron system
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• Ab initio lattice results for Fermi polarons in two dimensions
• High-precision numerical solution of the Fermi polaron problem and large-order behavior of its diagrammatic series
• Tunable Feshbach resonances and their spectral signatures in bilayer semiconductors
• Fermi polarons at finite temperature: Spectral function and rf-spectroscopy
• Crossover polarons in a strongly interacting Fermi superfluid
• Fulde-Ferrell-Larkin-Ovchinnikov state of two-dimensional imbalanced Fermi gases
• Fermi polaron revisited: polaron-molecule transition and coexistence
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• Thermodynamic signatures of the polaron-molecule transition in a Fermi gas
• Quartet Superfluid in Two-dimensional Mass-imbalanced Fermi Mixtures
• Microscopic model of the doping dependence of line widths in monolayer transition metal dichalcogenides
• Anomalous screening of quantum impurities by a neutral environment
• Nature of polaron-molecule transition in Fermi polarons
• Effect of fermion indistinguishability on optical absorption of doped two-dimensional semiconductors
• Crossover from exciton polarons to trions in doped two-dimensional semiconductors at finite temperature
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• Universal trimers emerging from a spin-orbit coupled Fermi sea
• Superconductivity induced by strong electron-exciton coupling in doped atomically thin semiconductor heterostructures
• Quantum Monte Carlo simulations of two-dimensional repulsive Fermi gases with population imbalance
• Emergence of Crystalline Few-body Correlations in Mass-imbalanced Fermi Polarons
• Rotons in Optical Excitation Spectra of Monolayer Semiconductors
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• Dimensional Crossover in a Spin-imbalanced Fermi gas
• Spectral Theory of the Fermi Polaron
• Stability of the two-dimensional Fermi polaron
• From Short-Range to Contact Interactions in Two-dimensional Many-Body Quantum Systems
• A smooth polaron-molecule crossover in a Fermi system
• Exact Quantum Virial Expansion for the Optical Response of Doped Two-Dimensional Semiconductors
• The self-energy of an impurity in an ideal Fermi gas to second order in the interaction strength
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• Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes
• Electronic properties and polaronic dynamics of semi-Dirac system within ladder approximation
• A Non-Gaussian Variational Approach to Fermi Polarons in One- and Two-dimensional Lattices
• Fermi spin polaron and dissipative Fermi-polaron Rabi dynamics
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• Exact calculation of spectral properties of a particle interacting with a one-dimensional Fermi gas in optical lattices
• Component exchange theory of trions
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• Observation of Magnon-Polarons in the Fermi-Hubbard Model
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• Momentum-dependent quasiparticle properties of the Fermi polaron from the functional renormalization group
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• Trapped imbalanced fermionic superfluids in one dimension: A variational approach
• Two-dimensional spin-imbalanced Fermi gases at non-zero temperature: Phase separation of a non-condensate
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• Composite polaron formed on surface of two-dimensional lattice system in weak coupling regime
• High Density Limit of the Fermi Polaron with Infinite Mass
• Super Fermi polaron and Nagaoka ferromagnetism in a two-dimesnional square lattice
• Spectral function of Fermi polarons at finite temperature from a self-consistent many-body $T$-matrix approach in real frequency
• Non-universal Fermi polaron in quasi two-dimensional quantum gases
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