Frequency-domain Hong-Ou-Mandel interference

TL;DR

This paper demonstrates a novel frequency-domain Hong-Ou-Mandel interference between two photons in a single spatial mode with different frequencies, enabling quantum interferometry via optical frequency multiplexing.

Contribution

It introduces the first frequency-domain HOM interference with photons in a single mode, expanding quantum interferometry architectures.

Findings

First demonstration of frequency-domain HOM interference in a single spatial mode.

Use of partial frequency conversion to achieve frequency multiplexing.

Potential for new quantum information processing architectures.

Abstract

Hong-Ou-Mandel (HOM) interference unveils a distinct behavior of identical particles which cannot be distinguished from each other. Especially for bosons, two separated identical particles passing through a beamsplitter always go together into one of the output ports, but that is not the case with other particles including fermions or classical ones. So far many elemental properties of quantum physics and information have been discovered through the concatenated HOM effects, which has been demonstrated in photons and recently in plasmons, atoms and phonons. However, all demonstrations in optical region employed two particles in different spatial modes. Here we first report the HOM interference between two photons in a single spatial mode with different frequencies (energies) by using a partial frequency conversion. The demonstrated frequency-domain interferometer allows us to replace spatial optical paths by optical frequency multiplexing, which opens up a distinct architecture of the quantum interferometry.