Dangers and Promise of Big Data

A Step Forward in Quantum Routing

The prospect of a quantum Internet has excited physicists for two decades. A quantum Internet will allow the transmission of information around the world with perfect security and make cloud-based quantum computing a reality.

But first, physicists must perfect the technology of quantum routing—the ability to receive and transmit quantum information without destroying it.

That’s a significant challenge. The key is a technique called quantum teleportation, which transmits information from one point to another without it passing through the space in between. This is a routine operation in any decent quantum optics lab but quantum routing—which concatenates the process—is another challenge altogether.

Today, Wolfgang Pfaff at the Kavli Institute of Nanoscience Delft in the Netherlands and a few pals say they’ve take a significant step toward this goal with the first demonstration of diamond teleporters that can act as nodes in a quantum network. “These results establish diamond spin qubits as a prime candidate for the realization of quantum networks for quantum communication and network-based quantum computing,” they say.

The fundamental difficulty in quantum routing is that quantum information is fragile stuff. So quantum teleportation has always involved creating a qubit, teleporting it and then immediately measuring it to check whether teleportation has been successful.

However, the process of measurement destroys quantum information. So an important goal is to create routers that can read and write quantum information without destroying it.

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Beyond the "Internet of Things:" the Industrial Internet

Perfect Bit Commitment Through Quantum Mechanics AND Relativity for 15 ms?

A breakthrough in quantum cryptography demonstrates that information can be encrypted and then decrypted with complete security using the combined power of quantum theory and relativity - allowing the sender to dictate the unveiling of coded information without any possibility of intrusion or manipulation.

Scientists sent encrypted data between pairs of sites in Geneva and Singapore, kept "perfectly secure" for fifteen milliseconds - putting into practice what cryptographers call a 'bit commitment' protocol, based on theoretical work by study co-author Dr Adrian Kent, from Cambridge's Department of Applied Mathematics and Theoretical Physics.

Researchers describe it as the first step towards impregnable information networks controlled by "the combined power of Einstein's relativity and quantum theory" which might one day, for example, revolutionise financial trading and other markets across the world.

'Bit commitment' is a mathematical version of a securely sealed envelope. Data are delivered from party A to party B in a locked state that cannot be changed once sent and can only be revealed when party A provides the key – with security guaranteed, even if either of the parties tries to cheat.

The technique could one day be used for everything from global financial trading to secure voting and even long-distance gambling, although researchers point out that this is the "very first step into new territory".

This is a significant breakthrough in the world of 'quantum cryptography' – one that was once believed to be impossible. The results are published in the journal Physical Review Letters.

"This is the first time perfectly secure bit commitment – relying on the laws of physics and nothing else – has been demonstrated," said Adrian Kent.

"It is immensely satisfying to see these theoretical ideas at last made practical thanks to the ingenuity of all the theorists and experimenters in this collaboration."

Any signal between Geneva and Singapore takes at least fifteen milliseconds – with a millisecond equal to a thousandth of a second. This blink-of-an-eye is long enough with current technology to allow data to be handed over encrypted at both sites, and later decrypted – with security "unconditionally guaranteed" by the laws of physics, say the team.

The researchers have exploited two different areas of physics: Einstein's special relativity – which interprets uniform motion between two objects moving at relative speeds – combined with the power of quantum theory, the new physics of the subatomic world that Einstein famously dismissed as "spooky".

Completely secure 'bit commitment' using quantum theory alone is known to be impossible, say researchers, and the "extra control" provided by relativity is crucial.

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