Observation and measurement of "giant" dispersive optical non-linearities in an ensemble of cold Rydberg atoms

TL;DR

This paper reports the observation and measurement of significant dispersive optical non-linearities in cold Rydberg atoms within an optical cavity, highlighting the role of Rydberg blockade in the non-linear response.

Contribution

It provides the first direct measurement of the Rydberg blockade effect on optical non-linearities in a cold atom ensemble inside a cavity.

Findings

Dispersive non-linearities are consistent with a Rydberg blockade model.

The 'blockaded fraction' of atoms can be directly estimated from measurements.

Experimental results agree with the theoretical model.

Abstract

We observe and measure dispersive optical non-linearities in an ensemble of cold Rydberg atoms placed inside an optical cavity. The experimental results are in agreement with a simple model where the optical non-linearities are due to the progressive appearance of a Rydberg blockaded volume within the medium. The measurements allow a direct estimation of the "blockaded fraction" of atoms within the atomic ensemble.