Polaron spectroscopy of interacting Fermi systems: insights from exact diagonalization

TL;DR

This paper investigates polaron spectral functions in interacting Fermi systems using exact diagonalization, exploring various background states and providing benchmarks for mean-field theories, with implications for cold atom and semiconductor experiments.

Contribution

It offers the first detailed exact-diagonalization analysis of polaron spectra in diverse Fermi environments, highlighting robust features and guiding future theoretical work.

Findings

Identification of robust spectral features across different Fermi backgrounds

Benchmarking of mean-field approaches against exact diagonalization results

Revealing surprising spectral phenomena that inspire new theories

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.