Emergence of spatial spin-wave correlations in a cold atomic gas
  Rydberg spin waves are optically excited in a quasi-one-dimensional atomic sample of Rb atoms. Pair-wise spin-wave correlations are observed by a spatially selective transfer of the quantum state onto a light field and photoelectric correlation measurements of the light. The correlations are interpreted in terms of the dephasing of multiply-excited spin waves by long-range Rydberg interactions. 
Y. O. Dudin, F. Bariani, and A. Kuzmich
physics.atom-ph quant-ph