What’s the deal with Google’s quantum chip

This chip, named "Willow," is the latest development in quantum computing, a field that leverages the principles of particle physics to create an entirely new category of computational power. According to Google, Willow incorporates significant “breakthroughs” and “paves the way to a useful, large-scale quantum computer.”

Despite these claims, experts have cautioned that Willow remains largely experimental, and a fully functional quantum computer capable of solving diverse real-world problems is still years, and potentially billions of pounds, away.

Understanding quantum computing

Quantum computers operate fundamentally differently from traditional computers found in phones and laptops. They exploit quantum mechanics, the peculiar behaviour of subatomic particles, to tackle problems much faster than classical systems.

Quantum computing holds the potential to accelerate complex tasks, such as drug development and material discovery. However, concerns have also been raised about its potential misuse, such as breaking encryption systems that safeguard sensitive data. In response to such risks, companies like Apple have begun to adopt quantum-resistant encryption measures, including making iMessage encryption “quantum proof.”

Willow’s capabilities and limitations

Hartmut Neven, the head of Google’s Quantum AI lab, described Willow as the most advanced quantum processor built to date. While he suggested that Willow could find some immediate practical applications, details remain sparse. According to Neven, commercially viable quantum applications are unlikely to emerge before the end of the decade. Initial uses might focus on simulating systems with significant quantum effects, such as nuclear fusion reactor design, pharmaceutical development, and battery innovation.

Despite these advancements, Professor Alan Woodward from Surrey University urged caution. He noted that while quantum computers excel in specific tasks, they are not designed to replace classical computers. Furthermore, he criticised using benchmark tests “tailor-made for a quantum computer,” arguing that such tests do not demonstrate universal advantages over classical systems. Nonetheless, he acknowledged Willow’s progress, particularly in addressing error correction.

The challenge of error correction

Error correction remains a critical hurdle in quantum computing. As the number of qubits—the fundamental units of quantum information—increases, so does the likelihood of errors. However, Google claims that Willow reverses this trend by reducing error rates across the system as more qubits are added, marking a major achievement in the field. Neven likened this breakthrough to enhancing the reliability of aircraft by adding more engines.

While these improvements are encouraging, even Google admits that error rates must drop further for quantum computers to achieve practical utility. Willow was developed in Google’s new manufacturing facility in California, reflecting the company’s significant investment in the technology.

Global interest in quantum computing

Quantum computing is attracting worldwide attention and investment. In the UK, the National Quantum Computing Centre (NQCC) was recently launched. Its director, Michael Cuthbert, described Willow as an “impressive milestone” rather than a true breakthrough, emphasising the importance of measured expectations. He highlighted quantum computing’s potential applications, such as optimising cargo distribution, telecom routing, and energy storage management.

The UK’s quantum sector currently supports 50 businesses, has attracted £800 million in funding, and employs 1,300 people. Meanwhile, researchers from Oxford University and Osaka University recently published findings on an alternative approach to quantum computing. Their trapped-ion qubit system operates at room temperature, unlike Willow, which requires ultra-low temperatures.

Scientific insights from Willow’s development were published in the journal Nature. While challenges remain, Google’s progress underscores the growing momentum in quantum computing research and development.