It told us something similar four years ago but this was challenged at the time by rivals, which argued that Google was exaggerating the difference between its machine and traditional supercomputers.

Howver, Google's's new paper — Phase Transition in Random Circuit Sampling — published on the open access science website ArXiv, demonstrates a more powerful device .

While Google's 2019 machine had 53 qubits, the building blocks of quantum computers, the next generation device has 70. Adding more qubits improves a quantum computer's power exponentially, meaning the new machine is 241 million times more powerful than the 2019 machine.

Steve Brierley, the chief executive of Cambridge-based quantum company Riverlane, said: "This is a major milestone. The squabbling about whether we had reached, or indeed could reach, quantum supremacy is now resolved."

“We estimate the computational cost against improved classical methods and demonstrate that our experiment is beyond the capabilities of existing classical supercomputers, the paper said.