Photon number conservation and photon interference
Mátyás Koniorczyk, József Janszky · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
The group theoretical aspect of the description of passive lossless optical four-ports (beam splitters) is revisited. It is shown through an example, that this approach can be useful in understanding interferometric schemes where a low number of photons interfere. The formalism is extended to passive lossless optical six-ports, their SU(3)-theory is outlined.