science

Google has made an eyebrow-raising claim, saying that its new quantum chip may be tapping into parallel universes to achieve its results.

The search giant recently unveiled a new quantum computer chip, dubbed Willow, which — on a specific benchmark, at least — the company says can outperform any supercomputer in the world.

"Willow’s performance on this benchmark is astonishing," Google Quantum AI founder Hartmut Neven wrote in a blog post announcing the chip. "It performed a computation in under five minutes that would take one of today’s fastest supercomputers 10²⁵ or 10 septillion years."

"This mind-boggling number exceeds known timescales in physics and vastly exceeds the age of the universe," he argued. "It lends credence to the notion that quantum computation occurs in many parallel universes, in line with the idea that we live in a multiverse, a prediction first made by David Deutsch."

Deutsch is a physicist who laid out his multiverse hypothesis in a 1997 book called "The Fabric of Reality," in which he suggested that quantum computers' calculations take place across multiple universes at the same time.

Put another way, Google is suggesting that its chip is so fast that its computations may have taken place across parallel universes — a bombastic statement that unsurprisingly drew plenty of skepticism online.

For one, the calculation Willow was tasked to solve wasn't really anything useful to anybody.

"The particular calculation in question is to produce a random distribution," German physicist and science communicator Sabine Hossenfelder tweeted in response to Google's announcement. "The result of this calculation has no practical use."

"They use this particular problem because it has been formally proven (with some technical caveats) that the calculation is difficult to do on a conventional computer (because it uses a lot of entanglement)," she added. "That also allows them to say things like 'this would have taken a septillion years on a conventional computer' etc."

Willow is a 100-qubit, or quantum-bit, chip. Unlike conventional computers, which use zeroes and ones for a binary system, quantum computers rely on qubits, which can be on, off, or — counterintuitively — both thanks to quantum entanglement, the mysterious phenomenon that allows particles to influence each other's states even when separated by distance.

"It's exactly the same calculation that they did in 2019 on a circa 50 qubit chip," Hossenfelder wrote.

At the time, Google made a similarly bombastic claim, arguing that it had achieved "quantum supremacy," or "the point where quantum computers can do things that classical computers can’t, regardless of whether those tasks are useful," as John Preskill, who first coined the term in 2012, wrote in a 2019 Quanta Magazine column.

That last part appears to be particularly relevant, given Google's latest claim.

"So while the announcement is super impressive from a scientific point of view and all, the consequences for everyday life are zero," Hossenfelder argued. "Estimates say that we will need about 1 million qubits for practically useful applications and we're still about 1 million qubits away from that."

The physicist also suggested that such wild claims may eventually "evaporate because some other group finds a clever way to do it on a conventional computer after all."

Google's claim of quantum supremacy drew immediate criticism in 2019, sparking a years-long feud between the company and quantum computing rival IBM. At the time, IBM researchers charged that Google had exaggerated its claims.

In a 2023 follow-up blog post, IBM researchers argued that the problem Google's quantum computer was instructed to solve in 2019 could be "performed on a classical system in 2.5 days and with far greater fidelity."

"This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced," the researchers wrote at the time.

In short, there's still a good reason to believe that Google's latest claim that Willow could be operating in the multiverse will be debunked. Apart from Deutsch's interpretation, researchers have also suggested that quantum particles are instead in a state of all positions before measurement, a theory known as the Copenhagen interpretation.

Where all of this leaves Google's breakthrough and its significance remains debatable.

But the company is already looking far ahead, promising to continue to scale up Willow to a point where it may actually become useful.

"This is the most convincing prototype for a scalable logical qubit built to date," Neven wrote in the announcement. "It’s a strong sign that useful, very large quantum computers can indeed be built."