# Electromagnetically induced transparency of ultralong-range Rydberg molecules

## TL;DR

This paper investigates how Rydberg molecule formation affects the storage and retrieval of Rydberg polaritons in ultracold atoms, revealing coherent revivals and a transition from few-state coherence to dephasing with increasing quantum number.

## Contribution

It demonstrates that a simple two-state model explains the observed phenomena across various quantum numbers, and identifies the transition to molecular state dephasing at higher levels.

## Key findings

- Coherent revivals in photon retrieval efficiency due to Rydberg molecules.
- A two-state model effectively describes the system for a range of quantum numbers.
- Transition from coherent evolution to dephasing as quantum number increases.

## Abstract

We study the impact of Rydberg molecule formation on the storage and retrieval of Rydberg polaritons in an ultracold atomic medium. We observe coherent revivals appearing in the retrieval efficiency of stored photons that originate from simultaneous excitation of Rydberg atoms and Rydberg molecules in the system with subsequent interference between the possible storage paths. We show that over a large range of principal quantum numbers the observed results can be described by a two-state model including only the atomic Rydberg state and the Rydberg dimer molecule state. At higher principal quantum numbers the influence of polyatomic molecules becomes relevant and the dynamics of the system undergoes a transition from coherent evolution of a few-state system to an effective dephasing into a continuum of molecular states.