Quantum Mechanics Could Solve Cryptography’s Random Number Problem


Peter Bierhorst’s machine is no pinnacle of design. Nestled in the Rocky Mountains inside a facility for the National Institute of Standards and Technology, the photon-generating behemoth spans an entire building. Its lasers, mirrors, and lenses are split among three laboratories, two of them at opposite ends of the L-shaped building. The whole thing is strung together with almost 900 feet of optical fiber. “It’s a prototype system,” the mathematician explains. “Something might drift out of alignment, and the whole thing stops working. It might take a few days to figure out what went wrong.”

On a good day, the machine produces 1,024 bits of data every 10 minutes, equivalent to typing 13 letters per minute. But it promises what even monkeys on typewriters can’t: completely random text.

It’s like this: Even if you repeat a quantum experiment by preparing a quantum particle in exactly the same initial state, subjecting it to the exact same conditions, measuring its orientation after the same amount of time, you can still end up with totally different results. This is unlike flipping a quarter, where its initial conditions—the force of your thumb, the direction of the winds—determine the outcome before it lands. The outcome of “flipping” a tiny quantum particle only exists as probabilities until the moment it “lands.” Electrons, photons, and atoms are really, actually random.

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