# Quantum method generates faster random numbers

PORTLAND, Ore. —Random numbers are usually not really random, since the methods by which a truly random number can be generated are few, far between and very slow to calculate. As a result, most applications in need of random numbers have to make do with pseudo-random numbers. Now researchers at the University of Illinois claim to have crafted a truly random number generation algorithm that is fast to execute.

"Our quantum method provides fast, secure random number generation at very high speeds," said professor Paul Kwiat. "Our method is 10-times faster than any other quantum random number generator reported so far."

The new method is based on shaping the optical pulses from a laser diode and then digitizing the time interval between random photon arrivals at a detector. Based on quantum mechanics, which insures that the measured interval is truly random, the method can nevertheless be tuned to execute as fast as 100 Mbits per second today, with the potential to achieve 10 Gbits per second with planned improvements to its laser driver circuit and detector.

A better random number generated create in the lab of professor Paul Kwiat, the Bardeen Professor of Physics and of Electrical and Computer Engineering at University of Illinois (Urbana). |

Kwiat, who performed the work with EE doctoral candidate Michael Wayne, said the new algorithm is compatible with a variety of applications, including data encryption, statistical analysis, and advanced numerical simulations.

Today these applications have to depend on pseudo-random methods based on deterministic calculations of a physical system, usually based on a "seed" starting value. Pseudo-random numbers can be generated as fast as the new method, but only produce numbers that are too computationally difficult to predict. Quantum methods, on the other hand, create truly random numbers, but are usually too slow since they rely on slow-operating single-photon detectors. But the new method combines the best of both worlds--high speed and guaranteed randomness.