Friday, August 27, 2010

China’s Secure Communications Quantum Leap

Via Jamestown Foundation (Aug 16, 2010) -

In May 2010 a team of 15 Chinese researchers from Tsinghua University in Beijing and the Hefei National Laboratory for Physical Sciences, a government-directed research center, published a research paper announcing a successful demonstration of “quantum teleportation” (liangzi yinxing chuan) over 16 kilometers of free space. These researchers claimed to have the first successful experiment in the world. The technology on display has the potential to revolutionize secure communications for military and intelligence organizations and may become the watershed of a research race in communication and information technology.

Although much of the science behind this technology is still young, quantum technologies have wide-ranging applications for the fields of cryptography, remote sensing and secure satellite communications. In the near future, the results from this experiment will be used to send encrypted messages that cannot be cracked or intercepted, and securely connect networks, even in remote areas, with no wired infrastructure, even incorporating satellites and submarines into the link.


As a result, the issue has found itself at the center of a rapidly developing geopolitical race to apply quantum technology to military and intelligence work. Since secure quantum key distribution (QKD) provides a much higher level of security between communication networks, employing quantum teleportation over a satellite network allows for completely secure communications, even in sensitive and remote areas, without fiber optic infrastructure, as long as all parties are able to maintain line of sight with a satellite. This could have wide applications in communications and intelligence for ground troops, aircraft, surface ships and submarines, and fits into China’s current plans to grow its satellite network even further.

Using quantum teleportation to send this type of information has been technically possible for several years, but according to the Chinese research paper, it had been previously demonstrated experimentally only over an enclosed fiber optics network and then only over a distance of several hundred meters. The Chinese experiment appears to shatter these records by claiming to be the first to use a high-powered blue laser to exchange quantum information over a free space channel, and to demonstrate the principle over a distance as great as 16 km. This distance is significant because it displays approximately the same degree of light distortion as is seen in communication from the earth’s surface to a satellite, and so would allow for quantum communication using satellites. If this experiment were indeed the first of its kind, it would appear that China has succeeded in leapfrogging the West, and gained a significant edge in next-generation communications and cryptography.

The Chinese claim to be the first may not be entirely accurate, although certain elements of their experiment were unique and innovative. In 2005, a group of universities and defense corporations under a Defense Advanced Research Projects Agency (DARPA) grant and led by BBN Technologies, the company responsible for developing the precursor to the internet, succeeded in transferring cryptographic keys over a free-space link of 23 km in Cambridge, Massachusetts. Well beyond the single link employed by the Chinese, the BBN program has developed an expanding, multi-node web of secure quantum communication that will be able to further expand and link seamlessly with existing internet technology. There are a few differences in the physics of their experiment that still make it notable and may not technically disqualify the Chinese from claiming their status as first, but nonetheless American researchers seem to have had a five-year head start in demonstrating the principles of the technology.

Because of its security level and applications for satellite and submarine communications, quantum communication technology figures centrally in the objectives of the Chinese military to upgrade their growing command and control capabilities. A functional satellite-based quantum communication system would give the Chinese military the ability to operate further afield without fear of message interception.

However, Chinese researchers must also be aware of the potential for the United States to employ the same technology and may be seeking ways to counter this eventuality. While it is still almost impossible to intercept quantum messages without being detected, it may be feasible to jam the laser signals that send them with “optical noise” or other lasers. Understanding the ways in which quantum cryptography functions may also eventually expose further weaknesses in the network that can be exploited by a savvy adversary. China’s continuing cutting-edge quantum cryptography, lasers and optics research thus seems as much a reaction to the same research in the United States and an attempt to counter it as it is to develop its own indigenous network.

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