We present the experimental realization of spatial quantum correlations of photons that are induced by multiple scattering of squeezed light. The quantum correlation relates photons propagating along two different light paths through the random medium and is infinite in range. Both positive and negative spatial quantum correlations are observed when varying the quantum state incident to the multiple scattering medium, and the strength of the correlations is controlled by the number of photons. The experimental results are in excellent agreement with recent theoretical proposals by implementing the full quantum model of multiple scattering.

Phys. Rev. Lett.

Smolka, S., Huck, A., Andersen, U. L., Lagendijk, A., & Lodahl, P. (2009). Observation of spatial quantum correlations induced by multiple scattering of nonclassical light. Phys.Rev.Lett., 102(Article number: 193901), 1–4. doi:10.1103/physrevlett.102.193901