China's Great (Quantum) Leap Forward

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Crew members of the Starship Enterprise use the transporter to teleport off the ship in the 1965 pilot episode of Star Trek

Like a pair of male turkeys puffing up their chests at each other, the U.S. and Chinese militaries are back at it again, engaging in tit-for-tat military exercises in the Yellow Sea. On Sept. 4, the Chinese navy finished live artillery maneuvers, using some of its newest planes, ships and battlefield weaponry in a publicly announced show of military strength. Though Chinese state media called the war games "routine," the timing of the event — just days before a scheduled U.S.-South Korea anti-submarine exercise in the same waters — suggests it's more likely an attempt to send the U.S. a simple message: This is our backyard.

After watching U.S.-led forces obliterate a Soviet-style Iraqi military in the first Gulf War, China realized it needed to improve its own outdated army. It has increased military expenditures every year for the past two decades. While Chinese officials called the relationship with the U.S. "stable" during talks in Beijing this week, given China's ambitions in the region, tensions between the two are sure to continue. Denny Roy, a senior fellow at the East-West Center in Honolulu, says China is "working towards a sphere of influence," and with their stronger military, they can now "send signals they couldn't before."

Thanks to a recent technological breakthrough, that's true literally, too. While China has been showing off its new hardware, a potentially more important military advancement has gone largely unnoticed: In May, Chinese scientists announced a demonstration of "quantum teleportation" over 16 kilometers (10 miles), creating what Matthew Luce, a researcher at the Defense Group Inc.'s Center for Intelligence Research and Analysis, calls "secure communications guaranteed by the laws of physics." China is now at the cutting-edge of military communications, transforming the field of cryptography and spotlighting a growing communications arms race.

While the People's Liberation Army won't be beaming up objects Star Trek-style anytime soon, the new technology could greatly enhance its command and control capabilities. Scientists use machines to manipulate units of light called photons. By changing the photons' quantum states and creating a new, readable pattern not unlike Morse code, they can pass on simple messages or encryption codes. A group of researchers from Tsinghua University and the Hefei National Laboratory for Physical Sciences entangled pairs of photons — linking them so changes to one photon will be instantaneously transferred to the other. Using a high-powered blue laser (the type China appears to be investing in for its submarine fleet), they then transported the quantum information farther than anyone had done before, their paper in Nature Photonics claims.

The process is called teleportation, but the information in the message is not actually moved. Instead, changes to one photon's quantum state will be adopted instantly by the other — something Einstein famously called "spooky action at a distance." The result is akin to having two pieces of paper 10 miles apart, and as a person writes on one paper the message simultaneously appears on the other.

Why is this superior to e-mail or radio? Because, theoretically, this method "cannot be cracked or intercepted," says Luce. If the photons in the laser beam are observed by a third party, the particles themselves will be altered due to a law of physics called the Heisenberg Uncertainty Principle, which states that measuring a particle alters it. As such, the sender and receiver would be immediately informed that someone was snooping.

At the 16km distance tested, China would be able to send these secure messages from its network of satellites to units on the ground. Luce also says the choice of a blue laser — instead of an infrared one like the U.S. has been testing — was chosen with its growing submarine fleet in mind since blue lasers penetrate farther underwater. Soon, Chinese satellites could be able to communicate with submarines without them needing to surface or give away their location by breaking radio silence. This may sound like science-fiction, but quantum encryption is already used by a few banks and governments for highly sensitive information on a smaller scale. The Chinese scientists write in Nature Photonics that a quantum communication network could be "within reach of current technology on a global scale."

The advance in secure communications comes none too soon. With ever-increasing computing power, the expiration date on today's cryptography techniques could be looming, Luce says. Right now, breaking modern encryption techniques require such computing power that one can change the code long before a computer has time to crack it. But "it's become very difficult to 'future proof' the encryption of data," Luce writes for the Jamestown Foundation. Tomorrow's computers will improve and data could suddenly become unprotected, while quantum teleportation, he says, "has a seemingly infinite time horizon."

Though the Chinese scientists claim in their peer-reviewed paper that this experiment communicated quantum information more than 20 times farther than previous tests over open space, this may not be entirely true. According to Luce in 2005, a group of universities along with defense corporations with a grant from the Defense Advanced Research Projects Agency (DARPA) transferred quantum information over 23 km (14 miles) in Cambridge, Massachusetts. Though Luce writes that a few differences in the DARPA project "may not technically disqualify the Chinese" from their claims, it's clear the U.S. military is also investing in this technology. Luce says it's difficult to know how far the U.S. is in developing quantum teleportation, "because a lot of the U.S. work is classified."

Of course, what's possible in theory — perfectly secure communication — is different from what will happen in practice. Luce suspects China's pioneering research in this technology is as much an attempt to find weaknesses in a possible U.S. quantum security network as it is to develop its own. Roy of the East-West Center says one of China's "pockets of excellence" is its cyber-warfare capability. If developed by the U.S., however, this technology could help neutralize China's ability to break into sensitive computer systems. Less than two weeks ago, researchers from Germany and Norway claim to have hacked a commercial quantum cryptography system by exploiting flaws in its detection equipment. It doesn't undermine the fundamental principle of secure quantum messaging, but it is a reminder that there is almost always a loophole. "The security of quantum cryptography relies on quantum physics but not only," Gerd Leuchs, a professor at the University of Erlangen-Nürnberg, says in a press release announcing the vulnerabilities. "It must also be properly implemented."

No one claims that the Chinese military will surpass the U.S.' anytime soon, but it isn't just dueling naval exercises that will determine pecking order. It's also how fast China can integrate the newest technologies into its military, maintaining its strengths like cyber-warfare while improving the PLA's precision, coordination and secrecy. In these ways, China has made a quantum leap forward.