Scalable generation and detection of on-demand W states in nanophotonic circuits

TL;DR

This paper presents a scalable method for generating and verifying 8-mode W states in nanophotonic circuits, combining innovative imaging and phase retrieval techniques to advance multipartite entanglement analysis.

Contribution

It introduces a reliable, scalable approach for creating and reconstructing multipartite W states in integrated photonic systems using Fourier and real-space imaging.

Findings

Successful generation of 8-mode W states in nanophotonic circuits

Implementation of Fourier and real-space imaging for state reconstruction

Use of entanglement witness to confirm entanglement

Abstract

Quantum physics phenomena, entanglement and coherence, are crucial for quantum information protocols, but understanding these in systems with more than two parts is challenging due to increasing complexity. The W state, a multipartite entangled state, is notable for its robustness and benefits in quantum communication. Here, we generate an 8-mode on-demand single photon W states, using nanowire quantum dots and a silicon nitride photonic chip. We demonstrate a reliable, scalable technique for reconstructing W-state in photonic circuits using Fourier and real-space imaging, supported by the Gerchberg-Saxton phase retrieval algorithm. Additionally, we utilize an entanglement witness to distinguish between mixed and entangled states, thereby affirming the entangled nature of our generated state. The study provides a new imaging approach of assessing multipartite entanglement in W-states, paving the way for further progress in image processing and Fourier-space analysis techniques for complex quantum systems.