Experimental investigations of the resonant dipole-dipole interaction between cold Rydberg atoms

Antoine Browaeys

 (Institut d’Optique, CNRS, Palaiseau, France)

This talk will present our on-going effort to control the dipole-dipole interaction between cold Rydberg atoms. In our experiment, we trap individual atoms in two-dimensional arrays of optical tweezers separated by few micrometers and excite them to Rydberg states using lasers. The arrays are produced by a spatial light modulator, which shapes the dipole trap beam. We can create almost arbitrary geometries of the arrays.

We have measured the van der Waals interaction between two individual atoms, and show efficient Rydberg blockade in arrays of three atoms. We have also demonstrated the control of the interaction between atoms with microwave and DC electric fields. We observe in particular the coherent energy exchange between two atoms resulting from their dipole-dipole interaction. This control of the interaction will find applications in quantum state engineering, quantum information and quantum simulation.

Bubble dynamics and acoustics: from water-saturated sands to volcanic slugs

Valérie Vidal

Laboratoire de Physique – CNRS Ecole Normale Supérieure de Lyon

Two-phase or three-phase flows are commonly found in geophysical phenomena, from soil liquefaction to volcanic explosions. Understanding and predicting their dynamics, however, still remains a challenge, due to the complexity of the materials involved and the difficulty of data acquisition in the field. Laboratory experiments reproducing one or several physical mechanisms involved in these natural processes represent a good opportunity to increase their understanding. I will present two examples currently investigated  in our laboratory: (1) Gas rising through a granular medium immersed in water ; and (2) The acoustics of bubble bursting. We will see how these ‘simple’ experiments may reveal a complex (and sometimes unexpected) behavior.