Google claimed quantum supremacy in 2019 — and sparked controversy

Competitors questioned whether the milestone had truly been achieved

Sycamore

Google's quantum computer Sycamore performed a calculation that would take thousands of years with a classical supercomputer, researchers claimed in 2019. An array of quantum computer chips is shown.

Google

Like Schrödinger’s cat, a 2019 claim of quantum supremacy seems to be simultaneously alive and dead.