The numbers have started to drift away from each other. They are no longer as close in value as they once were. This effect, that we call ‘fuzziness’, leads to an increased difficulty in finding the solution.

Ideally, Quantum Awesomeness should be played directly on a quantum computer. In this case, any mistakes made in finding the pairing of one puzzle will have consequences in all that follow. Specifically, all dots involved in the mistakes will experience a lot more fuzziness in later rounds. So the less mistakes you make, the easier the rest of the game will be.

This is the goal for the player. There will be a Game Over condition when the puzzles become too hard. So the player must try to make it through as many rounds as possible before that happens.

Well, that will be the goal for the player. But for the time being, it is the quantum computers that need to prove themselves. They need to show that they are actually capable of running the game. And of running it well.

Why will we need a quantum computer?

The basic gameplay described above could easily be implemented on a normal computer. Some procedure could easily be devised to cause the fuzziness.

But to live up to the quantum part of the name, we don’t just want any old fuzziness. We want to use the slow and steady built up of multipartite entanglement across a quantum processor. Then, once we are a sufficient number of rounds through a sufficiently large puzzle, our ‘simple’ game becomes something that even a supercomputer couldn’t run within its lifetime.

Under the hood, the game is throwing random pieces of quantum program. The player’s job is to keep order as long as possible. In this way, it is essentially a quantum cousin of Tetris. Image created using a figure from Google’s paper (left), and commons.wikimedia.org/wiki/File:Tetris_basic_game.gif (right).

This is related to the notion of so-called ‘quantum computational supremacy’, the point at which we prove that quantum computers can outperform normal ones (for some tasks, at least). In fact, the game is based on Google’s proposal for how to achieve this milestone, known as random circuit sampling (or RCS).

Put simply, what they want to do is run a fairly long quantum program on a fairly large device. The end result will be a fancy random number generator, where each of the possible outputs have almost the same probability. The almost here is very important, because it is the exact form of the slight differences in probabilities that will be hard to simulate with normal (or even super) computers. So by implementing this random number generator, it can be shown that a quantum processor can do something that non-quantum devices cannot.

In Quantum Awesomeness, the puzzle for each round is created by a small slice of random quantum program. By providing a solution, the player is unknowingly creating another snippet of quantum program. If the player’s solution is correct, this will undo the part that came before. But for each mistake that is made, a piece of the random program will remain. Once there have been enough mistakes, and the game becomes truly unplayable, the underlying quantum program will be just the kind that could use for RCS.

One major difference between the RCS approach and Quantum Awesomeness is the length of the program. Proposals for how to achieve ‘supremacy’ usually want to get it done as quickly and easily as possible. The quantum program at the heart of Quantum Awesomeness, however, is quite different. If the player gives good solutions to each puzzle, the effect is for one part of the program to undo what just came before. This means that it spends most of its runtime just faffing around.

The only way to avoid this is to have a completely incompetent player. Then things don’t get undone. In fact, the player’s solutions will be an extra contribution to building up the random circuit.

So the RCS proposal is equivalent to playing Quantum Awesomeness until Game Over, and then verifying that the Game Over was truly due to the expected quantum effects. But to do so as quickly as possible, the game can be played by only the most incompetent players.

This interpretation of what’s going on in the RCS proposal hopefully helps to provide a bit of perspective. Achieving ‘supremacy’, by this or any other means, is just one step along the long road to fully working quantum computers. It will be an important milestone to pass, but it won’t be the end of the journey. For that, we’ll at least need to let a moderately competent player manage to reach a fully quantum Game Over.

How well to current quantum devices perform?

The need to use the shortest possible quantum program is not due to impatience. It is as a protection against noise: the spurious effects that can contaminate our results. The faster a quantum program can be run, the less noise it will have to deal with.

Noise brings a new source of fuzziness to the numbers in the game. This means another source of difficulty, and one that has no respect for gentle learning curves.