Google moves toward quantum supremacy with 72-qubit computer

LOS ANGELES — Quantum computers are bulking up.

Researchers from Google are testing a quantum computer with 72 quantum bits, or qubits, scientists reported March 5 at a meeting of the American Physical Society — a big step up from the company’s previous nine-qubit chip.

The team hopes to use the larger quantum chip to demonstrate quantum supremacy for the first time, performing a calculation that is impossible with traditional computers (SN: 7/8/17, p. 28), Google physicist Julian Kelly reported.

Achieving quantum supremacy requires a computer of more than 50 qubits, but scientists are still struggling to control so many finicky quantum entities at once. Unlike standard bits that take on a value of 0 or 1, a qubit can be 0, 1 or a mashup of the two, thanks to a quantum quirk known as superposition. 

Nicknamed Bristlecone because its qubits are arranged in a pattern resembling a pinecone’s scales, the computer is now being put through its paces. “We’re just starting testing,” says physicist John Martinis of Google and the University of California, Santa Barbara. “From what we know so far, we’re very optimistic.” The quantum supremacy demonstration could come within a few months if everything works well, Martinis says.

Google is one of several companies working to make quantum computers a reality. IBM announced it was testing a 50-qubit quantum computer in November 2017 (SN Online: 11/10/17), and Intel announced a 49-qubit test chip in January.