Julian Kelly, director of Quantum Hardware at Google, announced Willow, the company's latest quantum chip. Willow has state-of-the-art performance across a number of metrics, enabling two major achievements.
1. 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.
2. Willow performed a standard benchmark computation in under five minutes that would take one of today's fastest supercomputers 10 septillion (10^25) years — a number that vastly exceeds the age of the Universe.
The Willow chip is a major step on a journey that began over 10 years ago. When Google Quantum AI was founded in 2012, 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 toward commercially relevant applications.
Here's a video with Kelly introducing Willow and its breakthrough achievements. Please turn on CC for auto-translated subtitle options. The subsequent sections will adopt a summarizing approach to present the content more concisely and effectively.
Exponential quantum error correction — below threshold!
Errors pose a significant challenge in quantum computing due to the susceptibility of qubits—the building blocks of quantum computation—to interact with their environment, leading to information loss. As the number of qubits increases, error rates typically rise, causing the system to behave like a classical computer.
In a study published in Nature, we demonstrated a groundbreaking result with Willow, showing that increasing qubits can reduce errors and enhance quantum behavior. By scaling qubit grids from 3x3 to 5x5 and 7x7, and leveraging advanced quantum error correction techniques, we consistently halved the error rate at each step.
This achievement represents an exponential reduction in error rates, a milestone known as "below threshold," where errors decrease as qubits scale. Meeting this benchmark, introduced by Peter Shor in 1995, signifies real progress in quantum error correction.
Notably, this includes one of the first demonstrations of real-time error correction on a superconducting quantum system—essential for maintaining computational integrity. Additionally, it showcases a "beyond breakeven" milestone, where qubit arrays outlast the lifetimes of individual physical qubits, proving that error correction enhances overall system performance.
As the first system to achieve below the threshold, Willow is the most credible prototype for scalable logical qubits to date, marking significant progress toward building large-scale quantum computers capable of solving commercially relevant problems beyond the reach of classical systems.
10 septillion years on one of today's fastest supercomputers
We assessed Willow's performance using the Random Circuit Sampling (RCS) benchmark, a standard pioneered by our team and widely adopted in the field. RCS serves as a baseline test, demonstrating whether a quantum computer can achieve tasks beyond the capabilities of classical systems—a critical benchmark for any quantum computing project.
Willow's RCS results are groundbreaking: it completed a computation in under five minutes that would take one of today's fastest supercomputers over 10 septillion years—far exceeding the age of the universe. This remarkable performance reinforces the concept of quantum computation leveraging vast parallelism, as theorized in multiverse models proposed by David Deutsch.
Our evaluation was conservative, granting classical supercomputers like Frontier full access to secondary storage without bandwidth constraints—an overly generous assumption. Despite expected improvements in classical computing, Willow's exponential advantage underscores the widening gap between quantum and classical systems. As we scale up, quantum processors are set to maintain this rapid trajectory of dominance.
State-of-the-art performance
Willow was developed in our state-of-the-art fabrication facility in Santa Barbara, purpose-built for quantum chip production. Designing and fabricating quantum chips requires seamless integration of all components—single and two-qubit gates, qubit reset, and readout—ensuring none fall short or hinder overall system performance.
Our process prioritizes maximizing system performance through a holistic approach, encompassing chip architecture, fabrication, gate development, and calibration. Rather than focusing solely on qubit quantity, we emphasize quality, as larger arrays of low-quality qubits offer limited utility. With 105 qubits, Willow excels in both quantum error correction and random circuit sampling, setting a new standard for system benchmarks.
Notable metrics include T1 times—measuring how long qubits retain their quantum state—which have improved fivefold to nearly 100 microseconds, highlighting significant advancements over previous chip generations.
What's next with Willow and beyond
The next milestone for quantum computing is achieving the first "useful, beyond-classical" computation relevant to real-world applications. We are optimistic that the Willow generation of chips can help realize this goal.
To date, experiments have fallen into two categories: performance-focused benchmarks like Random Circuit Sampling (RCS), which surpasses classical capabilities but lacks practical applications, and quantum system simulations that provide scientific insights yet remain within classical computing's reach. We aim to combine both—developing algorithms that outperform classical systems while addressing commercially relevant challenges.
To accelerate this progress, we offer open-source tools and educational resources, including a Coursera course on quantum error correction, empowering researchers and developers to contribute to advancing quantum algorithms for real-world solutions.
Quantum computing holds transformative potential, especially for AI. Its scaling advantages can revolutionize critical tasks like inaccessible data collection, training complex architectures, and modeling quantum-dependent systems. This includes breakthroughs in drug discovery, efficient battery design for EVs, and advancements in fusion and renewable energy technologies.
These groundbreaking applications, unattainable with classical systems, await the power of quantum computing to unlock their full potential.
