Generation of multiphoton entangled quantum states with a single silicon nanowire

TL;DR

This paper demonstrates the generation of bi- and multiphoton polarization entangled states using a single silicon nanowire waveguide, advancing integrated quantum photonics for quantum information processing.

Contribution

It introduces a simple integrated silicon nanowire source capable of producing high-fidelity multiphoton entangled states compatible with telecom systems.

Findings

Four-photon entanglement with 0.78 fidelity was achieved.

Multiphoton interference and quantum state tomography confirmed entanglement quality.

The device is compatible with dense wavelength division multiplexing.

Abstract

Multiphoton entanglement plays a critical role in quantum information processing, and greatly improves our fundamental understanding of the quantum world. Despite tremendous efforts in either bulk media or fiber-based devices, nonlinear interactions in integrated circuits show great promise as an excellent platform for photon pair generation with its high brightness, stability and scalability \cite{Caspani2017}. Here, we demonstrate the generation of bi- and multiphoton polarization entangled qubits in a single silicon nanowire waveguide, and these qubits directly compatible with the dense wavelength division multiplexing in telecommunication system. Multiphoton interference and quantum state tomography were used to characterize the quality of the entangled states. Four-photon entanglement states among two frequency channels were ascertained with a fidelity of $0.78\pm0.02$. Our work realizes the integrated multiphoton source in a relatively simple pattern and paves a way for the revolution of multiphoton quantum science.