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Analysis and Technology

Why quantum computers may continue to fail a key test

There have been several claims of quantum computers performing at a level impossible to match with a classical computer – most of which have been refuted. Could there be a mathematical reason why this keeps happening?

By Karmela Padavic-Callaghan

10 April 2025

model of a suspension of a quantum chip of a Quantum System Two

A model of a quantum computer

dpa picture alliance/Alamy

In 2019, Google claimed that its quantum computer, Sycamore, could complete calculations that would take 10,000 years to run on the world’s leading supercomputer – a feat of “quantum supremacy”. Last year, however, other researchers refuted Google’s claim by completing one of the calculations on a conventional computer in just 14.22 seconds. Undaunted, Google made a second claim for quantum supremacy a few months ago, with a new quantum computer called Willow. The firm estimated that a leading supercomputer would require 10 septillion years to match…

Article amended on 10 April 2025

We have amended this article to reflect that Quantinuum’s claim of quantum supremacy still stands

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