Experimental multi-photon-resolving detector using a single avalanche photodiode

A multichannel detector has been constructed using a single avalanche photodiode and a fiber-loop delay line. Detection probabilities of the channels can be set using a variable-ratio coupler. The performance of the detector is demonstrated on its capability to distinguish multi-photon states (containing two or more photons) from the one-photon state and the vacuum state.Received: 16 July 2003, Published online: 14 October 2003PACS: 42.50.Dv Nonclassical states of the electromagnetic field, including entangled photon states; quantum state engineering and measurements - 03.67.Hk Quantum communication