Explainer: What is Willow, Google’s breakthrough technology in quantum computing?

In an innovation that has left the technological world awestruck, Google has unveiled its quantum chip, Willow, a technology which paves the way for a large-scale quantum computer.

Pichai-Musk brainstorming session

As soon as a proud Google CEO Sundar Pichai announced the new technology on X, the social media platform’s boss, Elon Musk, replied with a “wow”. This started off a brainstorming session between the two on the possibility of making a quantum cluster in space, and harnessing solar energy on a larger scale to build a Kardashev’s Type II civilisation.

So what is Willow?

The quantum computing chip, built at Google’s state-of-the-art facility in Santa Barbara, California, is being called a breakthrough technology as it can exponentially reduce errors – a major challenge in quantum computing for almost 30 years now.

Willow is packed with 105 qubits – the basic units of information in quantum computing – marking a shift from the way classical computers function.

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While traditionally an increased number of qubits on a chip made it vulnerable to tiny disturbances like subatomic particles, increasing chances of errors, Willow keeps these issues at bay while effectively harnessing the speed of qubits.

Computation of 10 septillion years

Pichai shared in his post how the computing chip solved a standard benchmark computation in under five minutes which one of the fastest supercomputers would have taken 10 septillion years – more than the age of the Universe – to solve.

“We are past the break-even point,” said Google Quantum AI’s founder and head Hartmut Neven, stressing that the chip will play a revolutionary role in fields like medicine, Artificial Intelligence and energy optimisation where classical computing couldn’t make the cut.

Why Willow is a breakthrough technology?

Neven said errors have been a major challenge in quantum computing as qubits have a tendency to rapidly exchange information with their environment, making it difficult to protect the information needed to complete a computation.

“Typically the more qubits you use, the more errors will occur, and the system becomes classical,” he says.

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In contrast, in Willow, the more the qubits are used, the more it reduces errors, making the system more quantum instead of classical.

“As the first system below threshold, this is the most convincing prototype for a scalable logical qubit built to date. It’s a strong sign that useful, very large quantum computers can indeed be built. Willow brings us closer to running practical, commercially-relevant algorithms that can’t be replicated on conventional computers,” Neven says.

Can solve real-world problems

The correction of these errors in real time can help in solving real-world problems, claims Google.

The company sees Willow as an important step in the journey to build a useful quantum computer with practical applications in areas like drug discovery, fusion energy, and battery design.

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Hartmut says Willow has provided a significant impetus to a journey that began 10 years ago with a vision 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.”

Next challenge

Hartmut says the next challenge in the field will be to demonstrate a first “useful, beyond-classical” computation on today’s quantum chips that is relevant to a real-world application.