Quantum Turnstile Network: 200 Users Fully Protected ⚡ экспресс
A scalable fully connected quantum network based on Hong-Ou-Mandel (HOM) two-photon interference has been demonstrated, ensuring secure communication among users even with an untrusted provider. The network connected 200 nodes over distances up to 200 km with information-theoretic key security. Key components included integrated soliton microcombs and photonic chips, which enabled precise parallel generation and synchronization of multiple frequencies, high-contrast HOM interference, and measurement-device-independent quantum key distribution (MDI). This architecture opens the path to deploying fully connected MDI quantum networks on urban and intercity scales.
The quantum network works like a series of turnstiles that open only for a pair of perfectly synchronized photons. The central node tells them which turnstile to go to, but cannot forge the synchronization. 200 users can communicate with each other over distances up to 200 km—about the size of a large city.
To do this, two photons are sent to a half-silvered mirror. If they are identical, they always exit from the same side—like two people stepping into a turnstile in perfect unison. Any attempt to eavesdrop disturbs their synchronicity and is detected. From these joint passages, a key is born with complete randomness.
To create hundreds of identical pairs, they use a microscopic comb made of silicon nitride—it generates a rainbow of colors with precise spacing, like in a laboratory spectrometer. Photons travel at the speed of light and keep the secret even from the provider, who merely services the turnstiles.
🎯 The effect that makes photons 'march in step' was first demonstrated in 1987 by [scientist:Leonard Mandel]Leonard Mandel[/scientist] and colleagues. It works only for fully indistinguishable particles—the slightest imperfection breaks the synchronization. Today, this same trick underpins quantum teleportation and computing.