A year after china beat it the US is getting it’s own hackproof quantum network

A few years ago, Edward Snowden, a contractor working for the NSA, who recently released his own surveillance application for vulnerable reporters and individuals, leaked documents that showed the ways in which intelligence agencies were spying on our data. And one of the most striking revelations was that spies had tapped into the internet’s trans-oceanic fiber optic cables to monitor the vast amounts of information flowing through them.

Since then Snowden’s revelations have spurred efforts to tap the almost mystical properties of quantum science to make such hacking impossible by creating the world’s first truly unhackable, for now atleast, networks. And now there are signs of progress being made in both China, where they trialled the world's first quantum network earlier this year during a conference call with colleagues in Austria, and now, finally, in the US.

A startup called Quantum Xchange that is "pioneering unbreakable encryption" says it has struck a deal giving it access to 500 miles (805 kilometers) of fiber optic cable running along the east coast of the US to create what it claims will be the country’s first Quantum Key Distribution (QKD) network.

Also, recently the University of Chicago, Argonne National Laboratory, and the Fermi National Accelerator Laboratory announced a joint venture to create a test bed for an approach to secure data communication using quantum teleportation as the US races to catch up with China in the field.

The QKD approach used by Quantum Xchange works by sending an encoded message in classical bits while the keys to decode it are sent in the form of quantum bits, or qubits. These are typically photons, which travel easily along fiber optic cables. The beauty of this approach is that any attempt to snoop on a qubit immediately destroys its delicate quantum state, wiping out the information it carries and leaving a telltale sign of an intrusion.

The initial leg of the network, linking New York City to New Jersey, will allow banks and other businesses to ship information between offices in Manhattan and data centers and other locations outside the city securely.

However, sending quantum keys over long distances requires “trusted nodes,” which are similar to today’s internet repeaters that boost signals in a standard data cable. Quantum Xchange says it will have 13 of these along its full network and it’s at these nodes where the data becomes vulnerable again when the quantum keys are decrypted into classical bits and then returned to a quantum state for onward transmission.

During this phase in theory a hacker could steal the keys while they are briefly vulnerable which is why there are already several countries, including Canada and China, again, who are putting a lot of effort into either eliminating the use of nodes, by trying to leverage quantum satellite systems, and, or by improving the distance between the nodes which recently helped China build a 2,000km long quantum network.

Quantum teleportation eliminates this transmission risk by exploiting a phenomenon known as entanglement. This involves creating a pair of qubits, again, typically photons, in a single quantum state. A change in one photon immediately influences the state of the linked one, even if they are very far away from one another. In theory, data transmission based on this phenomenon is unhackable because tampering with one of the qubits destroys their quantum state. The challenges of making this work in practice are immense, and the approach is still confined to science labs.

“Sending a photon into a piece of fiber is not a big deal,” says David Awschalom, a professor at the University of Chicago, “but creating and sustaining entanglement is really challenging.” That’s especially true over long-distance cable networks.

Awschalom is leading the initiative involving the university and the national laboratories. The aim, he says, is to have the test bed enable a “plug-and-play” approach that will let researchers evaluate various techniques for entangling and sending out qubits.

The test bed, which will be built with several million dollars from the US Department of Energy and use a 30 mile stretch of fiber optic cable running between the labs, will be operated by members of the Chicago Quantum Exchange, which brings together 70 scientists and engineers from the three institutions. And as the number of countries who are all in their own races to build out the best and largest unhackable quantum networks increases Awschalom thinks it’s good to have healthy competition in the field.

“Other countries have pushed forward to build [quantum] infrastructure,” he says. “Now [the US] will do the same.”