Bi-photon propagation control with optimized wavefront by means of   Adaptive Optics
  We present an efficient method to control the spatial modes of entangled photons produced through SPDC process. Bi-photon beam propagation is controlled by a deformable mirror, that shapes a 404nm CW diode laser pump interacting with a nonlinear BBO type-I crystal. Thanks to adaptive optical system, the propagation of 808nm SPDC light produced is optimized over a distance of 2m. The whole system optimization is carried out by a feedback between deformable mirror action and entangled photon coincidence counts. We also demonstrated the improvement of the two-photon coupling into single mode fibers. 
M. Minozzi, S. Bonora, A. V. Sergienko, G. Vallone, and P. Villoresi
quant-ph physics.optics