Alexei Kitaev

A physicist at Caltech, originally from the Landau Institute in Moscow, with an unusual gift for finding structure where others see complexity.

In 1997 he proposed storing information in global, topological properties of a system of exotic particles called anyons, so that local noise cannot disturb it. The surface code that grew out of his toric code is the leading error-correcting scheme for hardware because it uses only neighbouring qubits on a flat chip. He also proposed in 2001 a wire that should host Majorana zero modes, the basis of Microsoft's long topological qubit programme, whose results remain contested.

Kitaev's surface code gave experimentalists a concrete target, with a relatively forgiving error threshold of about one percent. It is the code that Google's 2024 experiment (see below) used to show errors falling as it was made larger.