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NEWS

Dr. Matthias Weidemüller

Physikalisches Institut, Universität Heidelberg (Germany)

Monday, September 17th, 2012 at 12:00:00 PM  

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 04:05:38 PM on Tuesday, September 11th, 2012

Non-classical statistics of strongly-interacting dark-state Rydberg polaritons

Statistics of dark-state polaritons in an ultracold atomic gas produced by electromagnetically induced transparency.

Interfacing light and matter at the quantum level is at the heart of modern atomic and optical physics and is a unifying theme of many diverse areas of research. A prototypical realization is electromagnetically induced transparency (EIT), whereby quantum interference gives rise to long-lived hybrid states of atoms and photons called dark-state polaritons (see 10.1103/PhysRevLett.84.5094). Here we report the observation of strong interactions between dark-state polaritons in an ultracold atomic gas involving highly excited (Rydberg) states. By combining optical imaging with counting of individual Rydberg excitations we probe both aspects of this atom-light system. Extreme Rydberg-Rydberg interactions give rise to a polariton blockade, which is revealed by a strongly nonlinear optical response of the atomic gas. For our system the polaritons are almost entirely matter-like allowing us to directly measure the statistical distribution of polaritons in the gas. For increasing densities we observe a clear transition from Poissonian to sub-Poissonian statistics, indicating the emergence of spatial and temporal correlations between polaritons.

These experiments, which can be thought of as Rydberg dressing of photons, show that it is possible to control the statistics of light fields, and could form the basis for new types of long-range interacting quantum fluids.

For further informations, please contact Prof. Giovanni Modugno.