China Achieves Quantum Encryption Over 60 Miles of Fiber

Your credit card details, medical records, and private messages could all become vulnerable once quantum computers get powerful enough to crack today's encryption. But researchers just proved we can stay one step ahead.

A team in China successfully transmitted quantum-encrypted information across 100 kilometers of fiber optic cable, according to new research published in Science. That's roughly 60 miles—about the distance across a major metropolitan area—and represents a massive leap from the few hundred meters previously achieved.

The breakthrough uses device-independent quantum key distribution, or DI-QKD, which sounds complicated but works on a beautifully simple principle. Two particles become quantum entangled, meaning they're connected in a way that any snooping immediately disrupts their state. If someone tries to intercept your message, both sender and receiver know instantly.

Previous versions of this technology hit two major roadblocks. First, quantum particles lose their special properties quickly when traveling through fiber optic cables. Second, the devices used to boost their signal needed constant calibration, making them impractical for everyday use.

The Chinese research team solved both problems elegantly. They used single-photon interference to create quantum-entangled pairs on demand, only when conditions were perfect. Then they converted these quantum signals to telecom wavelengths, which travel through fiber with much less loss.

The results were striking. The team tested their system at distances of 11, 20, 50, 70, and 100 kilometers. At every distance, they maintained secure encryption and generated working security keys. Their entangling speed was orders of magnitude faster than previous experiments.

Why This Inspires

This isn't just about keeping secrets safe. Quantum networks could transform how we share medical data, conduct financial transactions, and protect critical infrastructure. The same technology could enable quantum computing networks where calculations happen across multiple connected quantum computers, exponentially increasing their power.

The research team notes their architecture could also generate truly random numbers for cryptography, test quantum devices without trusting their manufacturers, and serve as building blocks for scaling up quantum networks. Each application brings us closer to a quantum-powered future.

There's still work ahead. All the equipment sat in the same lab, and signal strength still decreases over distance due to fiber loss. But the path forward is clear: better fibers and improved frequency conversion could extend the range even further.

What once seemed like science fiction is now happening at city scale, bringing quantum-secure communications from proof-of-concept to real-world possibility.