The Quantum Internet Is Emerging, One Experiment at a Time

From Scientific American.com (June 19):

Today’s internet is a playground for hackers. From insecure communication links to inadequately guarded data in the cloud, vulnerabilities are everywhere. But if quantum physicists have their way, such weaknesses will soon go the way of the dodo.

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Although a fully realized quantum network is still a far-off vision, recent breakthroughs in transmitting, storing and manipulating quantum information have convinced some physicists that a simple proof-of-principle is imminent.

From defects in diamonds and crystals that help photons change color, to drones that serve as spooky network nodes, researchers are using a smorgasbord of exotic materials and techniques in this quantum quest. The first stage, many say, would be a quantum network using standard optical fiber to connect at least three small quantum devices about 50 to 100 kilometers apart.

Such a network may be built in the next five years, according to Ben Lanyon of the Institute for Quantum Optics and Quantum Information in Innsbruck, Austria. Lanyon’s team is part of Europe’s Quantum Internet Alliance, coordinated by Stephanie Wehner at the Delft University of Technology in the Netherlands, which is tasked with creating a quantum network. Europe is competing with similar national efforts in China—which in 2016 launched Micius, a quantum communications satellite—as well as in the United States. Last December, the U.S. government enacted the National Quantum Initiative Act, which will lavishly fund a number of research hubs dedicated to quantum technologies, including quantum computers and networks. “The main feature of a quantum network is that you are sending quantum information instead of classical information,” says Delft University’s Ronald Hanson. Classical information deals in bits that have values of either 0 or 1. Quantum information, however, uses quantum bits, or qubits, which can be in a superposition of both 0 and 1 at the same time. Qubits can be encoded, for example, in the polarization states of a photon or in the spin states of electrons and atomic nuclei. [read more]