Bringing the magic: Google breaks open a bottleneck in quantum computing

Google Quantum AI has demonstratively opened up a key bottleneck in quantum computing: we’ve shown that “magic state cultivation” works in practice on our Willow processor, reducing errors about 40x compared to without it. This breakthrough, published today in Science, is a crucial step towards scaling up quantum computing to practical use.

The "magic state" bottleneck

Since 2004, long before quantum computing was a practical engineering pursuit, researchers have foreseen a particularly tricky bottleneck.

To achieve “universal” quantum computing and execute useful programs, you need to be able to run (and error-correct) a specific set of quantum operations. You can do this by first creating what are called "magic states," so dubbed because they can help you create the operations you need for going beyond classical computing.

But there’s a catch: creating high-quality, error-corrected magic states is incredibly resource-heavy. Some estimates have shown that up to 95% of a quantum computer’s entire capacity might need to be dedicated to making them — leaving little room for actual computing. An extra challenge is that once you use a magic state, you can’t re-use it, making magic states a scarce resource.