Evidence of antiblockade in an ultracold Rydberg gas

TL;DR

This paper reports the experimental observation of antiblockade in an ultracold Rydberg gas, demonstrating control over pair excitation by tuning interactions and detunings, supported by spectroscopic measurements and a theoretical model.

Contribution

The study provides the first experimental evidence of antiblockade in ultracold Rydberg gases, with a novel control method and a detailed pair interaction model.

Findings

Antiblockade observed when coupling energy matches Rydberg interaction energy.

Spectroscopic measurements reveal variations in Rydberg pair distribution.

Model accurately reproduces experimental data and analyzes nearest neighbor distances.

Abstract

We present the experimental observation of the antiblockade in an ultracold Rydberg gas recently proposed by Ates et al. [Phys. Rev. Lett. 98, 023002 (2007)]. Our approach allows the control of the pair distribution in the gas and is based on a strong coupling of one transition in an atomic three-level system, while introducing specific detunings of the other transition. When the coupling energy matches the interaction energy of the Rydberg long-range interactions, the otherwise blocked excitation of close pairs becomes possible. A time-resolved spectroscopic measurement of the Penning ionization signal is used to identify slight variations in the Rydberg pair distribution of a random arrangement of atoms. A model based on a pair interaction Hamiltonian is presented which well reproduces our experimental observations and allows one to analyze the distribution of nearest neighbor distances.