News Feature: Code wars

Quantum cryptography gears up to fight code-breaking quantum computers. Will the approach bolster security in the future, or is it fatally flawed? In October 2014, an Antares rocket blasted off from a NASA launch pad on one of Virginia’s barrier islands, and exploded seconds later. In addition to about 5,000 pounds of food and equipment destined for the International Space Station, the doomed rocket was carrying 26 miniature satellites called CubeSats, one of which housed physicist Alexander Ling’s experiment. “We thought, ‘oh, that’s it, we’re not going to see our experiment again,’” recalls Ling, of the Centre for Quantum Technologies in Singapore. He was mistaken. Advances in quantum cryptography could enable the creation of a global quantum Internet. It would consist of networks on the ground, as well as in space, set up via satellites capable of exchanging photons in fragile quantum states. Image courtesy of Shutterstock/Login. Days later, Ling got a phone call. His experiment had washed up on a nearby beach. The CubeSat’s metal casing had been crushed—“a bit,” says Ling, but the experiment inside had not only survived but was still working. The nature of the experiment made this even more astonishing: Their device used crystals and lasers to generate particles of light, or photons, in delicate, easily destroyed quantum states. Neither the turbulence of the launch nor the shock of the explosion had knocked the device out of alignment. Ling was ecstatic. Although the mission had failed, his experiment had endured. He and other quantum cryptography researchers hope that expectations about the technology’s potential hold up just as well. Ling wants to help build a global quantum Internet in which computers would communicate securely using the quantum mechanical properties of particles of light. Such an effort would require both networks on the ground, built over existing …