An echo experiment in a strongly interacting Rydberg gas

TL;DR

This paper demonstrates the coherence of Rydberg excitations in a strongly interacting ultracold atomic gas using an optical rotary echo technique, revealing insights into dephasing times and interaction effects.

Contribution

It introduces an optical rotary echo method to verify coherence in strongly interacting Rydberg gases, a novel application in atomic physics.

Findings

Confirmed coherence of Rydberg excitations in the strong blockade regime

Measured dephasing times due to Rydberg interactions

Showed reversibility of excitation evolution via phase shifts

Abstract

When ground state atoms are excited to a Rydberg state, van der Waals interactions among them can lead to a strong suppression of the excitation. Despite the strong interactions the evolution can still be reversed by a simple phase shift in the excitation laser field. We experimentally prove the coherence of the excitation in the strong blockade regime by applying an `optical rotary echo' technique to a sample of magnetically trapped ultracold atoms, analogous to a method known from nuclear magnetic resonance. We additionally measured the dephasing time due to the interaction between the Rydberg atoms.