Google suggests that its quantum computer may use other universes to perform calculations

In case you missed it, Google announced some pretty impressive achievements in quantum computing on Monday. The announcement by the head of Google Quantum AI suggested that his quantum computer may have achieved these feats using calculations in another universe.

According to the internet giant, its new quantum chip called Willow can exponentially reduce errors because it uses more qubits. This is a major advance as errors and decoherence have been among the biggest challenges in quantum computing since its inception.

With the chip, Google says it is moving towards “commercially relevant” quantum computers. To do this, quantum computers must be able to outperform traditional computers, and Google says they can – at least on one particular task.

“Willow performed a standard benchmark calculation in less than five minutes that would take one of today’s fastest supercomputers 10 septillion (i.e. 10).²⁵) years – a number that far exceeds the age of the universe,” said Hartmut Neven, founder and head of Google Quantum AI, in a press release.

While that sounds impressive – and if you wanted that specific answer without waiting 10,000,000,000,000,000,000,000,000 years – the problem is that the task given to the computer isn’t that useful.

“The calculation in question is about generating a random distribution. 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 in a traditional way X (Twitter).

“It’s exactly the same calculation that they did in 2019 on an approximately 50-qubit chip. In case you haven’t been following, Google’s 2019 quantum supremacy claim was challenged by IBM pretty much immediately after the claim and several years later.” One group said they had done it on a traditional computer in a similar amount of time.

Although quantum computers are getting better and better, they are still far from being practical. In fact, just this year, Google launched a global competition offering $5 million to find practical uses for the machines.

While it’s exciting that Google is taking steps toward useful quantum computing, it’s not time to get too excited just yet. And it’s certainly not time to declare that we may be living in a multiverse.

This may seem strange, but it is made necessary by a strange claim hidden in Google’s announcement. According to Neven, the fact that the computer can perform such a calculation “lends credence to the idea that quantum computations occur in many parallel universes, consistent with the idea that we live in a multiverse, a prediction first made by David Deutsch .”

In other words, the head of Google’s quantum computing division believes that the work may be done in a different branch of the multiverse, such as the many-worlds interpretation of quantum mechanics.

Quantum computers use quantum mechanics to solve problems that are simply too complex for conventional computers or even supercomputers to calculate – at least in theory. While classical computers use gates to perform calculations and two states, ones and zeros, to represent information, quantum computers work probabilistically and are based on the wave/particle nature of matter.

“Quantum computers use changes in the quantum states of atoms, ions, electrons or photons. “Quantum computers link or entangle multiple quantum particles so that changes to one affect all others,” Sorin Adam Matei, associate dean for research at Purdue University, explains in an article for The Conversation.

“Then they introduce interference patterns, as if several stones were thrown into a pond at the same time. Some waves combine to form higher peaks, while other waves and troughs cancel each other out. Carefully calibrated interference patterns guide the quantum computer to the solution to a problem.

Since quantum computers are based on superposition, which assumes that particles are in many states before they are observed, this can lead to absurdities depending on your preferred interpretation of quantum mechanics.

In the Copenhagen interpretation, the particles are actually in this state of all positions before the measurement. In hidden variable theories (much less popular than the standard interpretation), the wave function is a mathematical description of what we observe, and we are missing something fundamental.

Then there is the many-worlds interpretation, where there is only the wave function and the entire universe is in a superposition. When observing, there is not a collapse but rather a bifurcation of the worlds.

Instinctively, one might think that this idea, which is certainly a fringe interpretation, would have a problem with quantum computers. But in the idea cited by Neven, Deutsch suggested that they work through “quantum parallelism.” According to this idea, the interference that quantum computers rely on occurs across universes (a result of the wave function not actually collapsing), ensuring that the desired outcome is more likely when measured.

While some, including Max Tegmark, have suggested that working quantum computers would prove the existence of the multiverse, this is really an exaggeration. Quantum computers are based on quantum mechanics and not on any specific interpretation of it, as far as we have evidence. They work according to the Copenhagen Interpretation and are also possible in hidden variable theories.

Although what Google has done with quantum computers is pretty neat, it is far from practical and is by no means evidence that it has performed calculations across many, many universes.