Strongly correlated growth of Rydberg aggregates in a vapor cell
  The observation of strongly interacting many-body phenomena in atomic gases typically requires ultracold samples. Here we show that the strong interaction potentials between Rydberg atoms enable the observation of many-body effects in an atomic vapor, even at room temperature. We excite Rydberg atoms in cesium vapor and observe in real-time an out-of-equilibrium excitation dynamics that is consistent with an aggregation mechanism. The experimental observations show qualitative and quantitative agreement with a microscopic theoretical model. Numerical simulations reveal that the strongly correlated growth of the emerging aggregates is reminiscent of soft-matter type systems. 
A. Urvoy, F. Ripka, I. Lesanovsky, D. Booth, J.P. Shaffer, T. Pfau, R.   L\"ow
physics.atom-ph cond-mat.quant-gas quant-ph