Direct observation of photon pairs at a single output port of a beam-splitter interferometer
Giovanni Di Giuseppe, Mete Atatüre, Matthew D. Shaw, Alexander V. Sergienko, Bahaa E. A. Saleh, Malvin Carl Teich, Aaron J. Miller, Sae Woo Nam, John M. Martinis · Physical Review A · 2003
Quantum theory predicts that two indistinguishable photons incident on a beam-splitter interferometer exit together (the pair emerges randomly from one port or the other). We use a special photon-number-resolving energy detector for a direct observation of this quantum-interference phenomenon. Simultaneous measurements from two such detectors, one at each beam-splitter-interferometer output port, confirm the absence of cross coincidences. Photon-number-resolving detectors are expected to find use in other quantum-optics and quantum-information-processing experiments.