Have Scientists Disproven Google’s Quantum Supremacy Claim?

Slashdot reader AltMachine writes: In October 2019, Google said its Sycamore processor was the first to achieve quantum supremacy by completing a task in three minutes and 20 seconds that would have taken the best classical supercomputer, IBM's Summit, 10,000 years. That claim — particularly how Google scientists arrived at the "10,000 years" conclusion — has been questioned by some researchers, but the counterclaim itself was not definitive. Now though, in a paper to be submitted to a scientific journal for peer review, scientists at the Institute of Theoretical Physics under the Chinese Academy of Sciences said their algorithm on classical computers completed the simulation for the Sycamore quantum circuits [possibly paywalled; alternative source of the same article] "in about 15 hours using 512 graphics processing units (GPUs)" at a higher fidelity than Sycamore's. Further, the team said "if our simulation of the quantum supremacy circuits can be implemented in an upcoming exaflop supercomputer with high efficiency, in principle, the overall simulation time can be reduced to a few dozens of seconds, which is faster than Google's hardware experiments". As China unveiled a photonic quantum computer which solved a Gaussian boson sampling problem in 200 seconds that would have taken 600 million years on classical computer, in December 2020, disproving Sycamore's claim would place China being the first country to achieve quantum supremacy.

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