Polaron spectroscopy of interacting Fermi systems: Insights from exact diagonalization

Abstract

Immersing a mobile impurity into a many-body quantum system represents a theoretically intriguing and experimentally effective way of probing its properties. In this work, we study the polaron spectral function in various environments, within the framework of Fermi-Hubbard models. Inspired by possible realizations in cold atoms and semiconductor heterostructures, we consider different configurations for the background Fermi gas, including charge density waves, multiple Fermi seas and pair superfluids. While our calculations are performed using an exact-diagonalization approach, hence limiting our analysis to systems of few interacting Fermi particles, we identify robust spectral features supported by theoretical results. Our work provides a benchmark for computations based on mean-field approaches and reveal surprising features of polaron spectra, inspiring new theoretical investigations.

Lattice polaron in a Bose–Einstein condensate of hard-core bosons

“…All these motivate further theoretical and numerical developments to understand lattice hard-core polarons beyond the Chevy ansatz-like approach. Due to the reduced dimensionality of the system, approaches such as exact diagonalization [52], quantum Monte Carlo, DMRG, or other sophisticated many-body techniques [94] may be suitable for studying these kinds of systems. Furthermore, an interesting avenue is to study the Fermi lattice polaron, which may reveal new physics such as the polaron-to-molecule crossover in a lattice, a phenomenon extensively studied in homogeneous confinements [95][96][97][98].…”

“…In optical lattices, impurity physics has renewed interest in probing the Mott-insulator to superfluid transition [40], topological phases [41][42][43], band geometry [44], magnetic polarons [45][46][47][48][49], few-body physics [50], non-equilibrium dynamics [51], and polaron physics in strongly correlated Fermi-Hubbard models [52]. The study of lattice polarons is further motivated by the advances in quantum gas microscopy, which enables the imaging of individual atoms [53,54], providing intricate spatial details of quantum states that complement traditional spectroscopic information [45,55].…”