A mesoscopic Rydberg impurity in an atomic quantum gas

TL;DR

This paper develops a new theoretical framework to describe the complex dynamics of Rydberg impurities in quantum Bose gases, revealing a crossover from molecular to superpolaronic states observable via spectral changes.

Contribution

It introduces a multiscale theoretical approach capturing the transition from few- to many-body Rydberg impurity dynamics in ultracold gases.

Findings

Spectral profile shifts from molecular lines to broad Gaussian distributions.

Identification of a crossover from few- to many-body states.

Temperature and density influence spectral signatures.

Abstract

Giant impurity excitations with large binding energies are powerful probes for exploring new regimes of far out of equilibrium dynamics in few- and many-body quantum systems, as well as for in-situ observations of correlations. Motivated by recent experimental progress in spectroscopic studies of Rydberg excitations in ensembles of ultracold atoms, we develop a new theoretical approach for describing multiscale dynamics of Rydberg excitations in quantum Bose gases. We find that the crossover from few- to many-body dynamics manifests in a dramatic change in spectral profile from resolved molecular lines to broad Gaussian distributions representing a superpolaronic state in which many atoms bind to the Rydberg impurity. We discuss signatures of this crossover in the temperature and density dependence of the spectra.