The wind of change is in the Willow – Google’s new AI chip
Google Quantum AI’s new chip promises error correction and performance that paves the way to a useful, large-scale quantum computer
- The first is that Willow can reduce errors exponentially as we scale up using more qubits. This cracks a key challenge in quantum error correction that the field has pursued for almost 30 years.
- Second, Willow performed a standard benchmark computation in under five minutes that would take one of today’s fastest supercomputers 10 septillion (that is, 1025) years — a number that vastly exceeds the age of the UniverseGoogle
The Willow chip is a major step on a journey that began over 10 years ago. The vision was to build a useful, large-scale quantum computer that could harness quantum mechanics — the “operating system” of nature to the extent we know it today — to benefit society by advancing scientific discovery, developing helpful applications, and tackling some of society’s greatest challenges. As part of Google Research, the team has charted a long-term roadmap, and Willow moves us significantly along that path towards commercially relevant applications.
As a measure of Willow’s performance, the team used the random circuit sampling (RCS) benchmark. Pioneered by our team and now widely used as a standard in the field, RCS is the classically hardest benchmark that can be done on a quantum computer today. You can think of this as an entry point for quantum computing — it checks whether a quantum computer is doing something that couldn’t be done on a classical computer. Any team building a quantum computer should check first if it can beat classical computers on RCS; otherwise there is strong reason for skepticism that it can tackle more complex quantum tasks. We’ve consistently used this benchmark to assess progress from one generation of chip to the next.
Willow’s performance on this benchmark is astonishing: It performed a computation in under five minutes that would take one of today’s fastest supercomputers 1025 or 10 septillion years. If you want to write it out, it’s 10,000,000,000,000,000,000,000,000 years. This mind-boggling number exceeds known timescales in physics and vastly exceeds the age of the universe.
These latest results for Willow, as shown in the plot below, are our best so far, but we’ll continue to make progress.
Computational costs are heavily influenced by available memory. Our estimates therefore consider a range of scenarios, from an ideal situation with unlimited memory (▲) to a more practical, embarrassingly parallelizable implementation on GPUs (⬤).
Our assessment of how Willow outpaces one of the world’s most powerful classical supercomputers, Frontier, was based on conservative assumptions. For example, we assumed full access to secondary storage, i.e., hard drives, without any bandwidth overhead — a generous and unrealistic allowance for Frontier. Of course, as happened after we announced the first beyond-classical computation in 2019, we expect classical computers to keep improving on this benchmark, but the rapidly growing gap shows that quantum processors are peeling away at a double exponential rate and will continue to vastly outperform classical computers as we scale up.
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