Google Says It Just Cracked One of Quantum Computing's Biggest Bottlenecks

In brief

• Google Quantum AI said Thursday that a technique called magic state cultivation cut errors about 40-fold on its Willow chip, producing magic states with 99.99% fidelity.
• Magic states are single-use resources needed to run useful quantum programs, and Google says some estimates put the cost of making them at up to 95% of a quantum computer's capacity.
• Cultivation is one of the tricks behind Google's 2025 estimate that RSA-2048 encryption could fall to under a million noisy qubits, though code-breaking would need magic states with errors near one in 10 billion.

Google says it has turned one of quantum computing's most promising paper tricks into something that actually works on a chip.

In a paper published in Science on Thursday, the company's Quantum AI team showed that a technique called magic state cultivation cut errors by about 40 times on its Willow processor.

Making quantum computers cheaper to build matters far beyond physics labs, because it brings forward the day they do useful work, like designing drugs and new materials, and also the day one could break the encryption that protects bank logins and Bitcoin wallets.

Quantum computers run on qubits—quantum bits that can hold a blend of 0 and 1 at once, letting them explore many answers in parallel. They are also absurdly fragile: a little heat or electrical noise can flip a qubit and wreck a calculation, which is why the whole industry is obsessed with error correction (spreading one piece of information across many qubits so mistakes can be caught and fixed).