Speaker: Antoine Browaeys, Institut d’Optique, Palaiseau, France

Title: Experimental investigations of resonant dipole-dipole interaction between cold atoms

Abstract:

This talk will present our on-going effort to understand and manipulate resonant dipole-dipole interaction between cold atoms. This interaction results from the non-radiative energy exchange between two-level systems, mediated by the vacuum field between atoms. It is long-range, with scaling between 1/R³ to 1/R, with R the distance between atoms.

We are working on two different systems of cold atoms where this interaction plays an important role. The first one is a dense ensemble of cold atoms confined in a volume on the order of the wavelength of an optical transition. Here the interaction results into the collective scattering of a near-resonant laser by the ensemble, described by a collection of eigen-modes. In particular the scattering is strongly suppressed with respect to the single atom case. The presence of this interaction leads to open question in the theory of the optical response of an ensemble of scatterers.

In our second systems, we manipulate individual atoms in arrays of optical tweezers separated by few micrometers. There we control the interaction between atoms with microwave and DC electric fields. We observe in particular the coherent energy exchange between two atoms. This control of the interaction has application in quantum state engineering.

Coffe and tea will be available from 10:00