Generation of doubly excited Rydberg states based on Rydberg antiblockade in a cold atomic ensemble

TL;DR

This paper investigates how off-resonant two-photon excitations and Rydberg interactions in cold atomic ensembles can generate doubly excited Rydberg states, highlighting optimal conditions for high-purity two-photon Fock state production.

Contribution

It introduces a detailed analysis of Rydberg anti-blockade effects in cold atoms, identifying optimal parameters for creating doubly excited states.

Findings

Enhanced probability of doubly excited states under optimal conditions

Large auto-correlation values indicating strong anti-blockade effects

Potential for high-purity two-photon Fock state generation

Abstract

Interaction between Rydberg atoms can significantly modify Rydberg excitation dynamics. Under a resonant driving field the Rydberg-Rydberg interaction in high-lying states can induce shifts in the atomic resonance such that a secondary Rydberg excitation becomes unlikely leading to the Rydberg blockade effect. In a related effect, off-resonant coupling of light to Rydberg states of atoms contributes to the Rydberg anti-blockade effect where the Rydberg interaction creates a resonant condition that promotes a secondary excitation in a Rydberg atomic gas. Here, we study the light-matter interaction and dynamics of off-resonant two-photon excitations and include two- and three-atom Rydberg interactions and their effect on excited state dynamics in an ensemble of cold atoms. In an experimentally-motivated regime, we find the optimal physical parameters such as Rabi frequencies, two-photon detuning, and pump duration to achieve significant enhancement in the probability of generating doubly-excited collective atomic states. This results in large auto-correlation values due to the Rydberg anti-blockade effect and makes this system a potential candidate for a high-purity two-photon Fock state source.