Brad Templeton discusses the vast computational power that a quantum computer could have, provided that someone were to build one. He compares this theoretical computer with a machine being marketed as a quantum computer, the D-Wave. Templeton is a Board Member and Former Chair of Electronic Frontier Foundation and the Track Chair for Computing at Singularity University.

Most people know or remember from school that underneath it all reality is not based on billiard balls and things that match our experience in the physical world, but on a system called quantum mechanics.  And the rules of quantum mechanics are rather strange and not very intuitive to us and so they don't act like the higher level rules that we've built computers on so far.  So there's a bunch of research to study whether or not you can do things in quantum mechanics that perform computation in ways that we can't do at the level of mechanical systems or electronic systems that we use.  In particular it seems possible in theory to do very, very huge amounts of computing in quantum mechanics, sort of as some people would imagine it as though you were tapping into millions and trillions and billions of parallel universes and having computations take place in all those parallel universes until an answer is found in one and is revealed to you in your universe.

Well, that's a little bit mystical.  I don't know if anyone can give you the true answer on that, but there are people who believe that they can make a computer that uses these properties of quantum computing to solve some very, very specific problems much, much faster than the way we solve them today with computers.  And when I say much, much faster, so much faster that if you were to turn the entire universe into an ordinary computer like the one on your desk, it still could not outcompete the quantum computer at solving these problems.  Now, one of the problems that can be solved this way, in theory, yet no one has built this computer that we know of, but one of the problems that can be solved is a math problem that we believe to be hard, which is to say factoring really large numbers.  And because we believe that problem to be really hard, we have used that as the lock in all of the computer security that we use in the world today, almost all of it.  And if that lock can be broken, because the quantum computer makes easy what everyone else believe to be incredibly hard, the person with the quantum computer could break most of the cryptography, all the traffic you see going across the web, a lot of the financial transaction traffic, a lot of the authentication, all of that stuff becomes vulnerable to a computer that's done that.

Now, Edward Snowden has told us that the NSA does indeed have a research project to build this, and I actually feel good about that because Snowden didn't tell us they already had one.  Now, the way you will know that someone has a quantum computer like this if it's made public, is you look out your window on Wall Street and if you see bankers and stock people running screaming in terror waving their arms you know that someone has developed a quantum computer.  There are a few other things that could cause that.  By the way many people are skeptical that it ever will happen.  There's some people who think something will always stand in the way of this being true.  But other people are very serious about it.  Now, there's a second type of device, which is also being called a quantum computer made by a company up in Vancouver called D-Wave.  The D-Wave Computer solves other specialty problems and not the one that affects cryptography.  It's, for example, good at solving a fairly hard problem.  Imagine you're out in a mountain range and you're in a valley somewhere in a mountain range and you're asked what's the lowest of valley in this mountain range?  Now, if you had to solve that yourself you'd have to like climb to the top of all the mountains and look down because in your valley it's easy to find the bottom of your valley, but you don't know if there's another valley over next to you that's lower or not.  And their quantum computer they claim is able to do things like solve that instantly, find that bottom of the valley.  Why is that useful?  Because that's a problem that we call optimization, having a really complex system and trying to find the most efficient, the lowest energy, the lowest cost way to deal with it.  And so that type of quantum computer could help us a lot at solving big business problems, big data problems.  That's actually very interesting too and they've actually sold a couple of these computers to have people who want to experiment on making that happen.  So two different things people call quantum computers.  Both capable of solving some very specific problems, which could have big consequences for our society, but not for example something that makes your spreadsheet go a lot faster.