# Quantum Rydberg Central Spin Model

## TL;DR

This paper introduces a new quantum impurity model involving Rydberg atoms, revealing unique dynamical features like spectrum renormalization and persistent spin oscillations, with implications for atomic physics and quantum chemistry.

## Contribution

It develops a novel variational approach to analyze Rydberg impurity dynamics, combining impurity-decoupling and Gaussian bath ansatz, uncovering features absent in traditional models.

## Key findings

- Interaction-induced renormalization of the absorption spectrum
- Long-lasting oscillations of the Rydberg-electron spin
- Novel features not explained by molecular bound states

## Abstract

We consider dynamics of a Rydberg impurity in a cloud of ultracold bosonic atoms in which the Rydberg electron can undergo spin-changing collisions with surrounding atoms. This system realizes a new type of the quantum impurity problem that compounds essential features of the Kondo model, the Bose polaron, and the central spin model. To capture the interplay of the Rydberg-electron spin dynamics and the orbital motion of atoms, we employ a new variational method that combines an impurity-decoupling transformation with a Gaussian ansatz for the bath particles. We find several unexpected features of this model that are not present in traditional impurity problems, including interaction-induced renormalization of the absorption spectrum that eludes simple explanations from molecular bound states, and long-lasting oscillations of the Rydberg-electron spin. We discuss generalizations of our analysis to other systems in atomic physics and quantum chemistry, where an electron excitation of high orbital quantum number interacts with a spinful quantum bath.