Multiple-Photons Resolving Detector using Fibre Ring

Optical devices able to resolve the number of photons of an optical pulse are very important in quantum state preparation and quantum communication. However, these devices are very hard to implement and an alternative is the multiple-photons resolving detector. Basically, it is an optical device able to distinguish optical pulses with 0 photons, one photon and more than one photon. In this work we show how to implement a different multiple-photon resolving detector using a fibre ring, polarising beam splitter and single-photon detectors.