Spatial interference of quantum mechanical particles exhibits a fundamental feature of quantum mechanics. A two-mode entangled state of N particles known as N00N state can give rise to non-classical interference. We report the first experimental observation of a three-photon N00N state exhibiting Young's double-slit type spatial quantum interference. Compared to a single-photon state, the three-photon entangled state generates interference fringes that are three times denser. Moreover, its interference visibility of 0.49±0.09 is well above the limit of 0.1 for spatial super-resolution of classical origin. The demonstration of spatial quantum interference by a N00N state composed of more than two photons represents an important step towards applying quantum entanglement to technologies such as lithography and imaging.
@article{arxiv.1009.5006,
title = {Observation of Young's Double-Slit Interference with the Three-Photon N00N State},
author = {Yong-Su Kim and Osung Kwon and Sang Min Lee and Heonoh Kim and Sang-Kyung Choi and Hee Su Park and Yoon-Ho Kim},
journal= {arXiv preprint arXiv:1009.5006},
year = {2015}
}