Sorbonne, Welinq and Leiden Demonstrate Private Quantum Networked Sensing With a Four-Photon GHZ State at 96.9 Percent Fidelity, arXiv 15 September 2026

A Sorbonne, Welinq, Lisbon and Leiden team ran the first laboratory demonstration of private quantum networked sensing on a four-photon GHZ state at 96.9 percent fidelity, estimating a joint phase while certifying that each node's local reading stays hidden even from a hostile network operator. We read what the 0.70 privacy bound means, why a coalition distributed sensor array or clock network is the defense case, and what separates a 10-hertz optical bench from an entangled sensor network a program office could rely on.