Quantum computing is closer to reality after another Google breakthrough

By Cade Metz

 

In 2019, a team of Google researchers said they had built a machine capable of performing tasks that were not possible with traditional supercomputers. They described this machine, called a quantum computer, as a turning point in the evolution of information technology.

 

Some scientists disputed the claim. In the years since, as traditional supercomputers grew more powerful, they matched the feats of Google’s quantum computer.

 

On Monday, Google unveiled a new quantum computer that may end this back-and-forth race with traditional machines and that points to a future in which quantum computers could drive advances in areas like drug discovery and artificial intelligence.

 

Google said its quantum computer, based on a computer chip called Willow, needed less than five minutes to perform a mathematical calculation that one of the world’s most powerful supercomputers could not complete in 10 septillion years, a length of time that exceeds the age of the known universe.

 

Quantum computing — the result of decades of research into a type of physics called quantum mechanics — is still an experimental technology. But Google’s achievement shows that scientists are steadily improving techniques that could allow quantum computing to live up to the enormous expectations that have surrounded it for decades.

 

“When quantum computing was originally envisioned, many people — including many leaders in the field — felt that it would never be a practical thing,” said Mikhail Lukin, a professor of physics at Harvard and a co-founder of the quantum computing start-up QuEra. “What has happened over the last year shows that it is no longer science fiction.”

 

Many other tech giants, including Microsoft, Intel and IBM, are building similar technology as the United States jockeys with China for supremacy in this increasingly important field. As the United States has pushed forward, primarily through corporate giants and start-up companies, the Chinese government has said it is pumping more than $15.2 billion into quantum research.

 

The mathematical calculation performed by Google’s machine was a test designed solely to gauge the progress of quantum computing — not a task that could be useful in other fields, like medicine. Google’s quantum computer also uses a form of error correction — a way of reducing mistakes — that could allow this kind of machine to reach its potential. In a research paper published on Monday in the science journal Nature, Google said its machine had surpassed the “error correction threshold”.

 

“What we really want these machines to do is run applications that people really care about,” said John Preskill, a theoretical physicist at the California Institute of Technology who specialises in quantum computing. “Though it still might be decades away, we will eventually see the impact of quantum computing on our everyday lives.”

 

A traditional computer like a laptop or a smartphone stores numbers in silicon chips and manipulates those numbers, adding them, multiplying them and so on. It performs these calculations by processing “bits” of information. Each bit holds either a 1 or a 0. But a quantum computer defies common sense. It relies on the mind-bending ways that some objects behave at the subatomic level or when exposed to extreme cold, like the exotic metal that Google chills to nearly 460 degrees below zero inside its quantum computer.

 

Quantum bits, or “qubits,” behave very differently from normal bits. A single object can behave like two separate objects at the same time. Scientists can build a qubit that holds a combination of 1 and 0. This means that two qubits can hold four values at once. And as the number of qubits grows, the computer becomes more powerful.

 

With its latest superconducting computer, Google has claimed “quantum supremacy,” meaning it has built a machine capable of tasks that are beyond what any traditional computer can do. But these tasks are esoteric. 

 

They involve generating random numbers that can’t necessarily be applied to practical applications, like drug discovery. 

 

Google and its rivals are still working toward what scientists call “quantum advantage,” when a quantum computer can accelerate the progress of other fields like chemistry and artificial intelligence or perform tasks that businesses or consumers find useful. The problem is that quantum computers still make too many errors. 

Making leaps

 

> Google’s new quantum computer is based on a chip called Willow, which needs <5 minutes to perform a calculation that one of the world’s most powerful supercomputers could not complete in 10 septillion yrs 

> Google has claimed “quantum supremacy” — meaning it has built a machine capable of tasks that are beyond what any traditional computer can do

  > But firm and its rivals are still working towards “quantum advantage” — when a computer can accelerate the progress of fields like chemistry and AI