Peking University researchers have demonstrated a quantum communication prototype capable of spanning 3,700 kilometers—enough to connect Beijing and Jakarta—using fingernail-sized chips that eliminate the security vulnerabilities of traditional relay stations. Led by Professor Wang Jianwei, the breakthrough published in Nature brings long-distance quantum networks one step closer to reality.
The numbers demand attention. 3,700 kilometers. That’s the aggregate networking distance achieved by a team from Peking University in a study published this week in Nature. Twenty users, each separated by 370 km of optical fiber, communicating with quantum-level security. No trusted relay nodes. No vulnerable handoffs between stations. Just light pulses carrying encryption keys that cannot be intercepted without leaving detectable traces.
Quantum key distribution (QKD) has long carried a paradoxical reputation. Theoretically, it represents the gold standard for secure communication—any eavesdropping attempt inevitably disturbs the quantum state, alerting sender and receiver. But practically, the technology has struggled with limited range, prohibitive equipment costs, and the inability to serve multiple users efficiently.
Existing systems rely on what engineers call “trusted relay nodes.” Think of them as secure courier stations where quantum keys change hands along the route. Functional, yes. But each node introduces a potential security gap—like sending a confidential package through multiple distribution centers where someone could theoretically peek inside.
READ ALSO: https://modernmechanics24.com/post/giant-godzilla-robot-powers-iter-fusion/
What problem does this research solve? It eliminates those nodes entirely. The Peking University team has demonstrated a network architecture where users communicate directly with a central server, removing the chain of intermediate trust points that made long-distance quantum networking vulnerable.
How does it actually work? At the server side sits a “super optical comb”—a low-frequency chip smaller than a fingernail that generates dozens of ultra-stable laser lines operating at identical frequencies. If traditional quantum communication resembles two people shouting across a windy valley, this optical comb functions as a perfectly synchronized metronome. Every user device operates from the same unwavering time base, with line widths as low as 40 hertz.
On the client side, the team built 20 independent quantum transmitter chips. Each integrates a complete suite of functions—essentially quantum telegraph operators receiving timing signals from the central comb, encoding key information onto light pulses, and shooting them through 370 km of optical fiber back to the server.
What sets this system apart? Manufacturability. Historically, quantum devices have been custom-built, hand-tuned, and prohibitively expensive. The Peking University team fabricated both server and client chips from mature industry wafers, demonstrating high performance, reproducibility, and operational yield—critical prerequisites for scalable quantum devices.
WATCH ALSO: https://modernmechanics24.com/post/blue-dogs-spotted-in-chernobyl-zone/
The experimental results underscore the system’s robustness. Of the 120 modulators on 20 randomly selected client chips, 117 functioned correctly. That’s a 97.5 per cent operational success rate. Each user pair communicated reliably across 370 km. Aggregate networking capacity across all 20 users reached 3,700 km.
Here’s the honest limitation, though. This system operates under carefully maintained laboratory conditions. It’s not yet ready for your office building or living room. Temperature, vibration, and environmental stability requirements remain stringent. The team acknowledges that transitioning from lab demonstrations to field deployments will require additional engineering.
Why does this matter? Because the architecture points toward something genuinely scalable. The system works with existing fiber infrastructure—quantum signals can share the same cables carrying conventional internet traffic. No specialized cabling required. Theoretically, this platform could scale to support hundreds of users with individual quantum links stretching up to 1,000 km.
The research team, led by Professor Wang Jianwei and executed by engineers at Peking University, has already charted the next phase: integrating single-photon detectors and optical frequency shifters onto the server chip, expanding the number of microcomb channels, and pushing toward practical deployment.
READ ALOS: https://modernmechanics24.com/post/china-nuclear-arsenal-pact-collapse/
For governments, financial institutions, and anyone handling data that must remain secret for decades, the implications are straightforward. Quantum key distribution offers security grounded in physics rather than computational complexity. If you can eliminate the relay nodes that represent its weakest links, you fundamentally change what’s possible in secure communications.
The Chinese researchers haven’t built a nationwide quantum network yet. But they’ve demonstrated a viable pathway to one—using chips mass-produced from standard wafers, compatible with existing fiber, and scalable to hundreds of users. That’s not a finished product. It’s a blueprint. And blueprints, once validated, tend to get built.
