Oh well, at least it's

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January 2015
February 2015

2015-01-16 »

After my wifi presentation, someone asked if I wanted a tour of the Institute for Quantum Computing (at the University of Waterloo). Well, yes, obviously.

So, we did that today.  If I were to summarize our discussion, I would summarize it thusly:

"Hmm, all that radio wave stuff you're doing just sounds like second year physics to me.  Look, here's the quantum entanglement machine I built.  We're going to put a balloon with a receiver into low earth orbit and then beam QUANTUM ENTANGLED LASERS INTO SPACE."

Yeah, okay, you win this round.

On that topic, if there's anybody in MTV who wants someone to come down and do a tech talk about beaming QUANTUM ENTANGLED LASERS INTO SPACE, I have a contact for you.

Seriously though, it's a real thing.  There's this sandwich of two crystals, and one photon ends up split into two half-powered photons of slightly different frequencies based on which crystal, and the two have opposite polarity (but the distribution of polarities is random), and then there's a passive splitter based on frequency, and yadda yadda, off you go!

It's called QKD, quantum key distribution.  The idea is you end up with a random bitstream encoded as the polarity of the stream of photons.  There are exactly two copies of this stream (with opposite polarities) and discovering the polarity destroys the beam, so you know if someone has intercepted it.  Once you have the random data, you can use that to power conventional symmetric encryption, which unlike RSA, is not yet theoretically defeated by quantum computing.

Apparently the bitrate is something around gigabits at ~1km range.  As distances get longer, bit rate decreases.  But you only need enough bits to generate useful symmetric keys, which is not much.

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