That rapid improvement has led to what’s being called “Neven’s law,” a new kind of rule to describe how quickly quantum computers are gaining on classical ones. The rule began as an in-house observation before Neven mentioned it in May at the Google Quantum Spring Symposium. There, he said that quantum computers are gaining computational power relative to classical ones at a “doubly exponential” rate — a staggeringly fast clip. ...Something this remarkable would surely be documented by a peer-reviewed scientific paper, right? I see no mention of one.
Doubly exponential growth is so singular that it’s hard to find examples of it in the real world. The rate of progress in quantum computing may be the first.
The doubly exponential rate at which, according to Neven, quantum computers are gaining on classical ones is a result of two exponential factors combined with each other. The first is that quantum computers have an intrinsic exponential advantage over classical ones ... The second exponential factor comes from the rapid improvement of quantum processors.
Our usual expert weighs in:
“I think the undeniable reality of this progress puts the ball firmly in the court of those who believe scalable quantum computing can’t work,” wrote Scott Aaronson, a computer scientist at the University of Texas, Austin, in an email. “They’re the ones who need to articulate where and why the progress will stop.”The answer comes next: the supposed progress may be all an illusion unless quantum supremacy is reached.
Google has been particularly vocal about its pursuit of this milestone, known as “quantum supremacy.”Neven works for Google. They often said 2016, then 2017, then 2018, and now 2019.
So far, quantum supremacy has proved elusive — sometimes seemingly around the corner, but never yet at hand. But if Neven’s law holds, it can’t be far away. Neven wouldn’t say exactly when he anticipates the Google team will achieve quantum supremacy, but he allowed that it could happen soon.
“We often say we think we will achieve it in 2019,” Neven said. “The writing is on the wall.”
For how many years can we have double exponential progress, and still no convincing demo that scalable quantum computing can work? Not many. We should have a verdict soon.