I'm currently reading the book Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything by Michio Kaku, and I came upon the following sentence:
Soon after Google made its claim of achieving quantum supremacy, the Chinese announced that they broke an even larger barrier, performing a calculation in 200 seconds that would take a digital computer half a billion years. (my emphasis)
How would it be possible to prove that something of that scale is correct or valid?
Other claims of quantum supremacy have been on the order of a classical computer taking 1,000 years and even that seems difficult to prove.
What evidence do researchers provide that Quantum Advantage has occurred?
I'm just trying to understand this more clearly.
Update: Also mentioned in Wikipedia article: Quantum Supremacy.
Although in this it says the classical computer would take 2.5 billion years.
"In December 2020, a group based in the University of Science and Technology of China (USTC) led by Jian-Wei Pan reached quantum supremacy by implementing gaussian boson sampling on 76 photons with their photonic quantum computer Jiuzhang. The paper states that to generate the number of samples the quantum computer generates in 200 seconds, a classical supercomputer would require 2.5 billion years of computation."