Image processing of two photons

LT13248A - The where-about of two photons along a one-dimensional line can be generally described by the probability of the two photons to have a certain combination of positions along the line. This is a two-dimensional distribution, as is, for example, the intensity distribution that makes up a classical image. There are many ways in which an image can be processed and manipulated. Could such methods be used for controlling the spatial distribution of two photons, even if it represents a highly non-classical, quantum state of light?

In this work we show that one of the most frequently used image processing techniques, namely, spatial frequency shaping, or "Fourier processing", can be adapted for the spatial manipulation of highly non-classical states of photon pairs. As an example, we demonstrate the retrieval of the two-photon quantum phase using an analog of classical phase-contrast microscopy. As many more Fourier processing algorithms can be applied, we believe that this opens up a new avenue for the manipulation of non-classical light.