Even You Can Help Build a Quantum Computer

Quantum computers hit the headlines every now and again. You will hear about how we are one step closer to building them, although, to most it is unclear what ‘they’ actually are. The development of quantum computation remains, in the public mind, a strange and mystic art that is beyond the reach of mortal men.

Image: Dano | CC BY 2.0

Fortunately, there have been some great projects launched in 2016 to solve this problem. For example, you can play with a real quantum computer using IBM’s Quantum Experience (I did some stuff with it myself, but that’s another story).

The blue and pink squares tell IBM’s five quantum bits what to do. By drag and drop you can make your own quantum computation. This example makes some fancy measurements.

With ScienceAtHome you can play games that tell scientists what to do in their labs. But that is not all. There are plenty of quantum games to try out, and more still to come in the future.

Let me tell you more about one project in particular though. This project is related to the science behind the recent Nobel Prize in Physics, as well as the even more recent Buckley Prize. A project that lets you become a scientist, or just pass the time while waiting for the bus. It is my own project called Decodoku.

Decodoku is funded by the NCCR QSIT, which is a network responsible for basically all things quantum that are going on in Switzerland. It is based on quantum error correction, which is the set of tools and techniques that quantum computers will need to ward off the effects of noise (more on that later). We package all this up into a set of games that let you take part in our research without having to worry about the quantum stuff.

The games are based on the most promising route towards quantum error correction: the so-called topological codes. These take some of the Nobel prize winningly exciting parts of the field of topological phases and harness them to help us make quantum computers. And the best part of it all is their ability to create impossible particles known as anyons.

In many phases of matter we can find little disruptions that are localized in a small area. Sometimes we can move these little disruptions around. And sometimes they behave as if they were particles, obeying all the rules that real particles do. For example, they refuse to appear from nothing, or to disappear into thin air, unless their antiparticle is around too.

You can also get these fake particles in phases of matter that are not topological. The problem is that they then always turn out to be bosons and fermions. These are the boring kinds of particles that you get in such boring places like CERN (and everywhere else in the universe).

The big difference with topological matter is that the fake particles are usually restricted to moving around in two dimensions. This gives us a little 2D universe to play with. The laws of physics would be different in the Flatland, since things we can do in 3D become impossible.

But with these impossibilities come new possibilities.

In a 2D universe, laws of physics emerge that do not make sense within the freedom of 3D. This gives us new particles - impossible particles - called anyons.

The easiest way to make a new universe in which anyons live is using dice. Here’s a quick how-to video for anyone who would like to whip one up during their tea break.

Anything can happen in an anyonic universe. This is not a pun on the word ‘any’. It is rather the actual etymology of the term. If you ever see the crazier types of anyon in action, you will understand why. Having the particles dance around each other can lead to strange things which can then be used to build a quantum computer. But the focus of the Decodoku project actually lies somewhere else.

We focus on overcoming the biggest hurdle: the noise. Because we are not the only ones who get to play with anyons, noise can too. The little gremlins of thermalization and stray interactions fiddle with our toy universe constantly. They can cause anyons to appear out of nowhere (though always with their anti-particle nearby). They can move them around. They can cause one anyon to decay into several ones, or a few to combine into one. The more exotic and useful our anyons are, the more exotic and annoying the noise can be. This is where quantum error correction comes in.

We have to keep an eye on the anyons. We have to spot those emerging where they should not, and going where they have no right to be. We have to shepherd them back to their antiparticles so that they can annihilate once more. We have to stop them getting out of control, or they will start messing with our quantum computer.

So this is our problem. This is the puzzle we have to solve. We have some anyons made by noise, and we have to work out the best way to keep them in check.

For the very simple types of anyons, we already have great tools to achieve this. Our friends from computer science have pre-made algorithms for solving problems in the mathematical field of graph theory. Luckily, it turns out that our problem in this case is just a simple problem of graph theory. Which means we can just download some code, use it, and feel very clever and scientific.

However, for complicated anyons, it is not that easy: our existing algorithms are rubbish, and computer scientists just shake their heads and utter strange acronyms.

When dressing this up to sound fancy, we say that our algorithms are heuristic. But that is just a ‘sciency’ way of saying that the public could probably do better than us.
Here’s a screenshot. No scary science. Just a fun puzzle.

If that is the case, we should ask the public for help. And so we did! We have developed games that distill the puzzle out of our problem. This can then be given to anyone to solve. My 4-year-old daughter, for example. She knows nothing about anyons (except that daddy’s job is to fight them), but she can have a good go at quantum error correction. And it is not just for kids. Actually adults dominated the games when I presented them at the Suisse Toy Expo in Bern recently. Our current high scorer is a middle-aged man who knows nothing about quantum mechanics whatsoever.

If you want to try knocking him off the top spot, you can check out our games here. They are completely free and always will be. And if you are brave enough to want to know more about the science behind them, then dive into our blog. Have fun being a quantum mechanic!

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