Earlier this month, China's official news agency Xinhua announced the launch of a secure quantum communications network between Shanghai and Beijing.
The 2,000 kilometer (1,243 mile) backbone will be used for military and government communications, but also in commercial areas such as banking.
That puts China far ahead of US and Europe, experts say.
Quantum key distribution adds a level of security for communications, since it protects encryption keys from being intercepted while in transit and allows for the use of symmetric keys.
Today, secure internet communications rely on asymmetric keys, with communications encrypted by a public key and decrypted by a different, private key, which is never shared. However, asymmetric encryption is weaker than symmetric encryption, where the same key is used for both encryption and decryption.
China’s quantum network is a significant milestone and impressive achievement, said Renato Renner, quantum physicist at Swiss Federal Institute of Technology.
"Although the basic technology for this has been available for several years, it is extremely challenging to implement it in a way that is robust enough to be suitable for commercial applications," he said.
This month's announcement, combined with China's quantum communications satellite, puts it into a leading position in this field, he said.
"China has developed a market for quantum key distribution that appears not to exist elsewhere, and now Chinese companies are actively productizing the technology," said Alexander Ling, researcher at the Center for Quantum Technologies at the National University of Singapore.
That's good news for China's emerging quantum communications industry and could potentially help China leapfrog over other countries, like the US, when it comes to technological leadership in this area.
"Market opportunities like these will allow the Chinese firms to move ahead of their international competitors simply because they will have the opportunity to refine the deployment and operational aspects of the technology," he said. "In turn, this will inspire more use-case research."
"Largest Quantum Network Ever Demonstrated"
The scale of the Chinese network is also significant.
There are already 242 nodes on their network, said Thomas Jennewein, physics professor and member of the Institute for Quantum Computing at University of Waterloo.
"To my knowledge, this is the largest quantum network that has ever been demonstrated," he said. Previous projects maxed out at half a dozen nodes.
One organization in the US that does have a small test project in the works is the Oak Ridge National Laboratory, but it's not comparable to the Chinese effort, said Jayson Hines, project manager in the Computing and Computational Sciences Directorate at Oak Ridge National Laboratory.
"The US at large does not have anything comparable to the China effort," he said.
The European Union, however, does have a large-scale project in the works, he said.
That's the 1 billion Euro (US $1.19 billion) quantum Flagship project scheduled to launch next year.
"Enterprises will be able to take advantage of the funding to do deployments in 2018," said Kelly Richdale, senior VP for quantum-safe security at ID Quantique, one of the participants in the project. "But companies will not be able to use it for secured transport for the first few years while it is being set up."
Another project is underway in the UK, where the government invested 270 million pounds (US $364 million) in a technology project that includes a quantum communications network with four hubs.
The first real deployments are scheduled to go live this year, Richdale said.
"The reason we haven’t rolled this out yet commercially is that the technology is still more expensive than classical security, not very fast, not very well integrated into standard networking hardware," said Alessandro Fedrizzi, quantum physicist at Heriot-Watt University.
But there have been some non-commercial projects, he said, including in the US, Europe, and also in the UK. Fedrizzi is involved with the latter.
"There have been some limited activities for securing real-world communication, such as in a Swiss election, but those were mostly publicity stunts," he said.
ID Quantique was involved in those activities, and, according to Richdale, they were more than that. "This was done by ID Quantique 10 years ago and is still being used," she said. "So no publicity stunt."
One problem is that the quantum networks currently rely on point-to-point links, which makes progress slow, since it requires quantum repeaters, which are still in their infancy.
"Another option would be to use satellites," Fedrizzi said. "China made some real progress on that front earlier this year, when they demonstrated quantum communication with a satellite, which in principle would allow global networks. China has had a head-start there, but there’s also credible efforts in many other places, such as Canada, Japan, and the EU."
How Important is Quantum Internet?
Using quantum key distribution to protect interception of keys in transit and for symmetric encryption is not a big deal right now, but that’s about to change.
"With the advent of quantum computers that can break the key distribution systems in use today, we do expect quantum key distribution to be used more widely in the future," said National University of Singapore's Ling.
"Advanced encryption is one of the primary commercial focus areas for quantum projects, mainly due to the rise in security threats we've seen over the past two to three years," said Charles King, principal analyst at Pund-IT, Inc.
Another alternative to using quantum key distribution is to use advanced new encryption technologies, such as lattice algorithms and elliptic curve algorithms, which are currently being tested and are expected to be secure even against super-fast quantum computers.
But quantum keys add an important level of security, said University of Waterloo's Jennewein, and can be used in combination with quantum-proof encryption algorithms for even more security.