Walborn = ‘Double-slit quantum eraser’ with double slit and eventually quarter wave plates. http://grad.physics.sunysb.edu/~amarch/Walborn.pdf [Broken] p. 5 section V: ”Figure 2 shows the standard Young interference pattern obtained with the double slit placed in the path of photon s, without quarter-wave plates QWP1 and QWP2, and with POL1 absent from detector Dp .” So he just detects p and obtains anyway interfere with the 's'-beam. We should then just have a different type of measurement on p – which do not give s interference - and we have a 'communication system'. One possibility would be a PBS (0) - which forces p photons to choose between becoming horizontally or vertically polarized. p. 2 section I: “Because of their momentum, time, and polarization correlation properties, photon pairs generated by spontaneous parametric down-conversion play an important role in the experimental demonstrations of quantum erasure” “Because of their […] polarization correlation properties” the s-photons then should be vertically and horizontally polarized. The vertically p-photons has been reflected - which gives a half wave difference. and “Because of their […] time […] correlation properties” this gives the horizontally s-photons also a half wave difference . Is this the argument? - So we need only a half silvered mirror at p to ensure that s consists of two types with half-wave of difference? ‘FTL’ because of coincidence counter - but with a greater distance to double slit and ideal conditions it maybe could work without.