Google's quantum supremacy challenged by ordinary computers, for now

The first example of "quantum supremacy" is when a quantum computer can complete a task that is impossible for ordinary computers. In the end, quantum computers will win out over the rest of the field, according to the search engine giant.

In order to achieve quantum supremacy, it was necessary to verify that a sample of numbers output by a quantum circuit have a truly random distribution. IBM's Summit, the world's most powerful computer, would take 10,000 years to achieve the same result, according to the team.

The Chinese Academy of Sciences in Beijing has created an improved method for a non-quantum computer that can solve the random sampling problem much faster than a quantum computer. The researchers were able to skip some of the calculations without affecting the final output.

The researchers were able to complete the task in less than 15 hours. They say this shows that a classical computer approach still works.

It could solve the problem in a few dozens of seconds if they were able to run their algorithm efficiently on an exascale computer. The first public exascale machine went online this year.

Although the improvements to the classical algorithm are impressive, comparing quantum hardware from 2019 with cutting-edge classical hardware like an exascale supercomputer ignores the likely gains in quantum computing research over the past three years.

He says that it was obvious at the time that there would be some development of better classical algorithms that would try to compete with the quantum computer.

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He concedes that classical computers are unlikely to keep up with quantum machines for certain tasks, but that his team's method is more efficient. He says that eventually quantum computers will have an advantage over classical computing.

Although it is the strongest challenge, the study from Zhang's team isn't the first one. IBM claimed that Summit could have completed the task in two and a half days, but it didn't run the experiment, even on a small scale like the team did.

The main point of the statement is that quantum technology improves rapidly. We don't believe that the classical approach can keep up with quantum circuits in the future.

The physical review letters were published in the press.