Google officially announced last week in the journal Nature that it achieved the milestone of “quantum supremacy.” This phrase, coined by the physicist John Preskill in 2012, refers to the first use of a quantum computer to make a calculation much faster than we know how to do it with even the fastest supercomputers available. The calculation doesn’t need to be useful: much like the Wright Flyer in 1903, or Enrico Fermi’s nuclear chain reaction in 1942, it only needs to prove a point.
Over the last decade, together with students and colleagues, I helped develop much of the theoretical underpinning for quantum supremacy experiments like Google’s. I reviewed Google’s paper before it was published. So the least I can do is to try to explain what it means.