Creating random numbers the quantum way


The stream of high quality papers continues from the lab of Andrew Shields at Toshiba Research in Cambridge, UK. Today, his team unveils a new type of quantum random number generator and a fine looking machine it appears to be.

Here’s the idea. Create a stream of single photons are emitted at random intervals that depend entirely on quantum processes–an attenuated continuous wave laser should do the trick. Fire them at a gated photon detector which accurately records their (entirely random) arrival time. The arrival time within a gated time period is then a random number ready for use in quantum cryptography or whatever app you happen to need it for.

The team uses the souped up photodiode that we saw a couple of weeks back to make the photon detections at rates of 4MB/s. And Shields says 100MB/s is possible–that’s two orders of magnitude faster than existing quantum random number generators.

What’s more, the new device is much simpler than other quantum random generators. One popular approach is to send a photon through a beam splitter and see which way it goes. In principle, the outcome is perfectly random but in practice it ain’t because it’s almost impossible to make a beam splitter with perfect 50% probability split.

In practice, the data from these devices needs a certain amount of massaging which can be costly and time-consuming.

So Shields looks to be on a roll.  Exciting times in his lab.

Ref: A High Speed, Post-Processing Free, Quantum Random Number Generator

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