Google LLC today published a scientific paper in which it said that a 53-qubit, superconducting chip running at one of its research labs has demonstrated so-called quantum supremacy for the first time.

Quantum supremacy describes the expected ability of quantum computers to perform complex calculations too difficult for even the most sophisticated classical machines. Google claims that its chip, dubbed Sycamore, managed to successfully complete such a calculation.

The operation involved finding patterns in random numbers generated by the processor’s own qubits. Sycamore produced a set of accurate results in about three minutes and 20 seconds. Google claims the same task would have taken over 10,000 years to complete on the world’s largest supercomputer, the 200-petaflop Summit system operated by the U.S. Energy Department. 

The paper, a copy of which was accidentally leaked last month, has received a somewhat mixed reception in the academic community. Researchers who spoke with the New York Times compared Google’s milestone to the first successful airplane flight executed by the Wright brothers in 1903. But scientists at IBM Corp., which is developing its own quantum chips, have called into question the search giant’s claim of a breakthrough.

The experts argued in a blog post published ahead of the paper’s release that the calculation done by Sycamore is, in fact, solvable on a classical computer. They cited an IBM analysis that had shown Summit could theoretically handle the task given a sufficient amount of storage hardware. “We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity,” the researchers detailed.

Other players in the quantum computing market have greeted the news with cautious optimism. “This achievement, if it holds up under the intense scrutiny that is sure to follow, represents a landmark academic achievement,” said Michael Biercuk, chief executive of Sequoia-backed quantum software startup Q-CTRL Pty. Ltd. Intel Labs head Rich Uhlig stressed that quantum computers are still far from commercial viability but congratulated Google on the news.

Moreover, it’s just a first step, said Constellation Research Inc. analyst Holger Mueller.

“While getting their first is the prize of hard work and tons of investment of the key players, it’s not critical for the adoption of quantum computing,” he said. “It’s the first gate the technology has to pass. Now it’s all about reducing complexity, lowering total cost of ownership and getting quantum -powered next-generation apps to coexist with traditional apps.”

Building a chip capable of outdoing a supercomputer was no easy feat. Researchers at the Santa Barbara, California-based Google lab where Sycamore was created had to develop a new, more reliable qubit design based on superconducting metals to stave off calculation errors. 

“We achieved this performance using a new type of control knob that is able to turn off interactions between neighboring qubits. This greatly reduces the errors in such a multi-connected qubit system,” Google quantum computing leads John Martinis and Sergio Boixo explained. “We made further performance gains by optimizing the chip design to lower crosstalk, and by developing new control calibrations that avoid qubit defects.”

Google has been involved in the race to commercial quantum computers for more than a decade. It joined the fray back in 2006 when a member of its research staff, Hartmut Neven, launched a project to explore how the technology could be applied to machine learning. The company now has a dedicated quantum computing group and actively collaborates with a number of universities.

Photo: Google