On-chip quantum interference between the origins of a multi-photon state

TL;DR

This paper demonstrates on-chip quantum interference between different origins of a four-photon state, revealing a new form of multi-photon nonlinear interference with potential applications in quantum information and fundamental physics.

Contribution

It experimentally shows quantum coherent superposition of multi-photon states from different sources on a silicon chip, enabling new interference phenomena and fundamental studies.

Findings

Controlled quantum superposition of photon origins achieved

Quantum interference demonstrated between different photon creation pathways

Potential for studying nonlocality with spatially separated photons

Abstract

Path identiy induces a broad interest in recent years due to the foundation for numerous novel quantum information applications. Here, we experimentally demonstrate quantum coherent superposition of two different origins of a four-photon state, where multi-photon frustrated interference emerges from the quantum indistinguishability by path identity. The quantum state is created in four probabilistic photon-pair sources on one integrated silicon photonic chip, two combinations of which can create photon quadruplets. Coherent elimination and revival of distributed four-photons are fully controlled by tuning phases. The experiment gives rise to peculiar quantum interference of two possible ways to create photon quadruplets rather than interference of different intrinsic properties of photons. Besides many known potential applications, this new kind of multi-photon nonlinear interference enables the possibility for various fundamental studies such as nonlocality with multiple spatially separated locations.