
When light propagates through multiple scattering media such as clouds, white paint, or nano-photonic devices, classical information for example the direction of propagation tends to be lost. Surprisingly this turns out to be different for quantum light. Now, Stephan Smolka and co-workers published in Physical Review Letters 102, 193901 (May 2009) the experimantal demonstration that spatial quantum correlations are induced when quantum correlated light is sent through a multiple scattering medium. As a consequence, the number of photons scattered into one direction can be predicted from the number of photons detected in a different direction. The magnitude of the spatial quantum correlations could be controlled by changing the quantum state of light incident on the medium.