Testing multi-photon interference on a silicon chip

TL;DR

This paper demonstrates multi-photon interference in a silicon photonic chip with high efficiency, enabling larger-scale quantum experiments by combining bright quantum sources with complex interferometers.

Contribution

It introduces a method to integrate high-efficiency quantum light sources with silicon circuits for multi-photon interference experiments.

Findings

Interfered up to 5 photons in 15 modes

Verified genuine multi-photon interference

Compared results with models including photon distinguishability

Abstract

Multi-photon interference in large multi-port interferometers is key to linear optical quantum computing and in particular to boson sampling. Silicon photonics enables complex interferometric circuits with many components in a small footprint and has the potential to extend these experiments to larger numbers of interfering modes. However, loss has generally limited the implementation of multi-photon experiments in this platform. Here, we make use of high-efficiency grating couplers to combine bright and pure quantum light sources based on ppKTP waveguides with silicon circuits. We interfere up to 5 photons in up to 15 modes, verifying genuine multi-photon interference by comparing the results against various models including partial distinguishability between photons.