Functional-renormalization-group approach to strongly coupled Bose-Fermi mixtures in two dimensions
arXiv:2104.14017 · doi:10.1103/PhysRevA.105.013317
Abstract
We study theoretically the phase diagram of strongly coupled two-dimensional Bose-Fermi mixtures interacting with attractive short-range potentials as a function of the particle densities. We focus on the limit where the size of the bound state between a boson and a fermion is small compared to the average interboson separation and develop a functional-renormalization-group approach that accounts for the bound-state physics arising from the extended Fröhlich Hamiltonian. By including three-body correlations we are able to reproduce the polaron-to-molecule transition in two-dimensional Fermi gases in the extreme limit of vanishing boson density. We predict frequency- and momentum-resolved spectral functions and study the impact of three-body correlations on quasiparticle properties. At finite boson density, we find that when the bound-state energy exceeds the Fermi energy by a critical value, the fermions and bosons can form a fermionic composite with a well-defined Fermi surface. These composites constitute a Fermi sea of dressed Feshbach molecules in the case of ultracold atoms while in the case of atomically thin semiconductors a trion liquid emerges. As the boson density is increased further, the effective energy gap of the composites decreases, leading to a transition into a strongly correlated phase where polarons are hybridized with molecular degrees of freedom. We highlight the universal connection between two-dimensional semiconductors and ultracold atoms and we discuss perspectives for further exploring the rich structure of strongly coupled Bose-Fermi mixtures in these complementary systems.
28 pages, 12 figures
References in corpus (26)
- Many-Body Physics with Ultracold Gases
- Exact evolution equation for the effective potential
- Attractive and repulsive Fermi polarons in two dimensions
- Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series
- Normal state of a polarized Fermi gas at unitarity
- 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
- Fluctuations in the quark-meson model for QCD with isospin chemical potential
- Polaron-molecule transitions in a two-dimensional Fermi gas
- Highly polarized Fermi gases in two dimensions
- Ground state of a tightly bound composite dimer immersed in a Fermi Sea
- Electron-exciton interactions in the exciton-polaron problem
- Polarons and Molecules in a Two-Dimensional Fermi Gas
- Renormalization Group Theory for the Imbalanced Fermi Gas
- Particle-hole fluctuations in the BCS-BEC Crossover
- Decay of polarons and molecules in a strongly polarized Fermi gas
- Flow equations for spectral functions at finite external momenta
- Quantum Monte Carlo Study of a Resonant Bose-Fermi Mixture
- Bound states in a quasi-two-dimensional Fermi gas
- Bose-Fermi Pair Correlations in Attractively Interacting Bose-Fermi Atomic Mixtures
- Rotons in a hybrid Bose-Fermi system
- Diagrammatic Monte Carlo study of quasi-two-dimensional Fermi-polarons
- Condensed phase of Bose-Fermi mixtures with a pairing interaction
- Superfluidity near phase separation in Bose-Fermi mixtures
- Thermodynamic signatures of the polaron-molecule transition in a Fermi gas
- In Situ Momentum Distribution Measurement of a Quantum Degenerate Fermi Gas using Raman Spectroscopy