Scalable Generation and Detection of on-Demand W States in Nanophotonic Circuits

Quantum physics phenomena,entanglement and coherence,are crucialfor quantum information protocols, but understanding these in systemswith more than two parts is challenging due to increasing complexity.The W state, a multipartite entangled state, is notable for its robustnessand benefits in quantum communication. Here, we generate eight-modeon-demand single-photon W states, using nanowire quantum dots anda silicon nitride photonic chip. We demonstrate a reliable and scalabletechnique for reconstructing the W state in photonic circuits usingFourier and real-space imaging, supported by the Gerchberg-Saxtonphase retrieval algorithm. Additionally, we utilize an entanglementwitness to distinguish between mixed and entangled states, therebyaffirming the entangled nature of our generated state. The study providesa new imaging approach of assessing multipartite entanglement in Wstates, paving the way for further progress in image processing andFourier-space analysis techniques for complex quantum systems.

Automated summary

In this study, an eight-mode on-demand single-photon W state is generated using nanowire quantum dots and a silicon nitride photonic chip. The W state is reconstructed in photonic circuits using Fourier and real-space imaging, supported by the Gerchberg-Saxton phase retrieval algorithm. The entangled nature of the generated state is confirmed by utilizing an entanglement witness. This study provides a new imaging approach for assessing multipartite entanglement in W states, contributing to the progress in image processing and Fourier-space analysis techniques for complex quantum systems.