High-visibility multi-photon interference for classical light

In quantum optics, considerable attention is paid to generating multi-photon states. In numerous attempts to do it, high visibility of higher-order interference is usually recognized as a 'signature' of nonclassical behaviour. Using Young's double-slit scheme, we demonstrate, theoretically and experimentally, that the classical visibility limit of multi-photon interference is quite high: 81.8 % for the third-order interference and 94.4 % for the fourth-order interference.