Dynamics of atoms within atoms

TL;DR

This paper investigates the quantum-many-body dynamics of atoms within a Rydberg atom in Bose-Einstein condensates, highlighting the effects of electron-atom interactions and the evolution of density waves and heating.

Contribution

It applies Gross-Pitaevskii and Wigner theories to model atom dynamics within Rydberg states, emphasizing the importance of interaction potential details.

Findings

Electron-atom interaction details significantly influence initial condensate response.

Density waves outside the Rydberg region are less affected by interaction potential details.

Condensate heating has minor impact on mean-field dynamics.

Abstract

Recent experiments with Bose-Einstein condensates have entered a regime in which thousands of ground-state condensate atoms fill the Rydberg-electron orbit. After the excitation of a single atom into a highly excited Rydberg state, scattering off the Rydberg electron sets ground-state atoms into motion, such that one can study the quantum-many-body dynamics of atoms moving within the Rydberg atom. Here we study this many-body dynamics using Gross-Pitaevskii and truncated Wigner theory. Our simulations focus in particular on the scenario of multiple sequential Rydberg excitations on the same Rubidium condensate which has become the standard tool to observe quantum impurity dynamics in Rydberg experiments. We investigate to what extent such experiments can be sensitive to details in the electron-atom interaction potential, such as the rapid radial modulation of the Rydberg molecular potential, or p-wave shape resonance. We demonstrate that both effects are crucial for the initial condensate response within the Rydberg orbit, but become less relevant for the density waves emerging outside the Rydberg excitation region at later times. Finally we explore the local dynamics of condensate heating. We find that it provides only minor corrections to the mean-field dynamics.