An experimental study of nonclassical effects in two-photon interferometry

Elna M. Nagasako, Sean J. Bentley, Robert W. Boyd +1 more

Luigi A. Lugiato, G. Strini

P. Hariharan

Xue-xiang Xu, Hong‐Chun Yuan, Ma Shan-Jun

We theoretically generate nonclassical states from a coherent state heralded by Knill–Laflamme–Milburn (KLM)-type interference. Injecting a coherent state in signal mode and two single-photon sources in the other two auxiliary modes of KLM-type interferometry, a broad class of useful nonclassical states is obtained in the output signal port after making two single-photon-counting measurements in the two output auxiliary modes. The nonclassical properties, in terms of the antibunching effect and the squeezing effect as well as the negativity of the Wigner function, are studied in detail by adjusting the interaction parameters. The results show that the input coherent state can be transformed into non-Gaussian states with higher nonclassicality after measurement induction. The maximum squeezing of our generated states is about 1.97928 dB.

Y. J. Lu, Z. Y. Ou

Geoff J. Pryde, Jeremy L. O’Brien, White, AG +4 more

Elements of the coincidence-CNOT (controlled-NOT) are experimentally demonstrated, which includes a bright photon source with good spatial mode quality; nonclassical interferometry; improved photon detection; and tomographic analysis. The logical circuit of the coincidence-CNOT is described in the paper.