Realizing a Compact, High-Fidelity, Telecom-Wavelength Source of Multipartite Entangled Photons

Abstract

Multipartite entangled states are an essential building block for advanced quantum networking applications. Realizing such tasks in practice puts stringent requirements on the characteristics of the states in terms of fidelity and generation rate, along with a desired compatibility with telecommunication network deployment. Here, we demonstrate a photonic platform design capable of producing high-fidelity Greenberger-Horne-Zeilinger (GHZ) states, at telecom wavelength and in a compact and scalable configuration. Our source relies on spontaneous parametric down-conversion in a layered Sagnac interferometer, which only requires a single nonlinear crystal. This enables the generation of highly indistinguishable photon pairs, leading by entanglement fusion to four-qubit polarization-entangled GHZ states with fidelity up to $(94.73\pm 0.21)\%$ with respect to the ideal state, at a rate of 1.7Hz. We provide a complete characterization of our source and highlight its suitability for practical quantum network applications.

References in corpus (23)

• Experimental ten-photon entanglement
• A wavelength-tunable fiber-coupled source of narrowband entangled photons
• Phase-stable source of polarization-entangled photons using a polarization Sagnac interferometer
• 12-photon entanglement and scalable scattershot boson sampling with optimal entangled-photon pairs from parametric down-conversion
• Maximum Likelihood, Minimum Effort
• Experimental demonstration of graph-state quantum secret sharing
• Quantum State Tomography via Linear Regression Estimation
• Joint Spectral Characterization of Photon-Pair Sources
• Experimental Verification of Multipartite Entanglement in Quantum Networks
• Multi-path entanglement of two photons
• Experimental quantum conference key agreement
• Efficient generation of high-dimensional entanglement through multi-path downconversion
• A pulsed Sagnac source of narrowband polarization-entangled photons
• Anonymity for practical quantum networks
• CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer
• Design Considerations for High-purity Heralded Single Photon Sources
• Conference key agreement in a quantum network
• Fully guided-wave photon pair source for quantum applications
• Experimental Quantum Multiparty Communication Protocols
• Unconditionally secure digital signatures implemented in an 8-user quantum network
• Experimental anonymous quantum conferencing
• Private network parameter estimation with quantum sensors
• Direct generation of multi-photon hyperentanglement