Unfortunately it is not an analysis of the math used in Joint Configurations, which would have been nice. The single-photon case of reflection off a hard boundary reversing phase is obvious from the requirements of meshing with classical physics, but where the pi/2 rotation comes from in the post is unclear.
http://en.wikipedia.org/wiki/Hong%E2%80%93Ou%E2%80%93Mandel_effect#!!!!!!
Unfortunately it is not an analysis of the math used in Joint Configurations, which would have been nice. The single-photon case of reflection off a hard boundary reversing phase is obvious from the requirements of meshing with classical physics, but where the pi/2 rotation comes from in the post is unclear.