Non-classical two-photon interference between independent telecom light pulses converted by difference-frequency generation

TL;DR

This paper demonstrates non-classical two-photon interference between independent photons at telecommunication wavelengths, achieved through wavelength conversion, advancing fiber-based quantum communication technologies.

Contribution

The study experimentally shows high-visibility Hong-Ou-Mandel interference between independently generated photons after wavelength conversion to telecom bands.

Findings

Visibility of $0.76\u00b1 0.12$ confirms non-classical interference

Wavelength conversion enables interference of photons from different sources

Progress toward fiber-based quantum communication

Abstract

We experimentally demonstrated the Hong-Ou-Mandel (HOM) interference between two photons after visible-to-telecommunication wavelength conversion. In the experiment, we prepared a heralded single photon by using spontaneous parametric down-conversion and the other photon from a weak laser source at 780 nm. We converted the wavelength of both photons to the telecommunication wavelength of 1522 nm by using difference-frequency generation in a periodically-poled lithium niobate, and then observed the HOM interference between the photons. The observed visibility is $0.76\pm 0.12$ which clearly shows the non-classical interference of the two photons. The high-visibility interference is an important step for fiber-based quantum communications of photons generated from visible photon emitters.