Experimental interference of uncorrelated photons

TL;DR

This paper demonstrates two-photon interference effects using uncorrelated photons with different frequencies, showing that classical-like interference patterns can occur even without photon correlation, challenging traditional views.

Contribution

The study provides experimental evidence of two-photon interference with uncorrelated photons, highlighting similarities to correlated photon interference and expanding understanding of quantum interference phenomena.

Findings

Interference fringes depend on phase terms related to single-photon and two-photon states.

Interference features are similar for correlated and uncorrelated photons in single-photon counting.

Differences include coincidence event validity and spectral bandwidth considerations.

Abstract

The distinguishing of the multiphoton quantum interference effect from the classical one forms one of the most important issues in modern quantum mechanics and experimental quantum optics. For a long time, the two-photon interference (TPI) of correlated photons has been recognized as a pure quantum effect that cannot be simulated with classical lights. In the meantime, experiments have been carried out to investigate the classical analogues of the TPI. In this study, we conduct TPI experiments with uncorrelated photons with different center frequencies from a luminescent light source, and we compare our results with the previous ones of correlated photons. The observed TPI fringe can be expressed in the form of three phase terms related to the individual single-photon and two-photon states, and the fringe pattern is strongly affected by the two single-photon-interference fringes and also by their visibilities. With the exception of essential differences such as valid and accidental coincidence events within a given resolving time and the two-photon spectral bandwidth, the interference phenomenon itself exhibits the same features for both correlated and uncorrelated photons in the single-photon counting regime.