John Preskill on Quantum Computing

From Y Combinator:

John Preskill is a theoretical physicist and the Richard P. Feynman Professor of Theoretical Physics at Caltech.

He once won a bet with Steven Hawking, which as he writes made him “briefly almost famous.” John and Kip Thorne bet that singularities could exist outside of black holes and after six years Hawking conceded that they were possible in very special, “nongeneric” conditions.

In this episode we cover what John’s been focusing on for years: quantum information, quantum computing, and quantum error correction.

What was the revelation that made scientists and physicists think that a quantum computer could exist?

John Preskill – The idea caught on about 10 years later when Peter Shore made the suggestion that we could solve problems which don’t seem to have anything to do with physics, which are really things about numbers like finding the prime factors of a big integer. That caused a lot of excitement in part, because the implications for cryptography are a big disturbing. But then physicists, good physicists– Started to consider, can we really build this thing?

Some concluded and argued fairly cogently that no, you couldn’t because of this difficulty that it’s so hard to isolate systems from the environment well enough for them to behave quantumly. It took a few years for that to sort out sort of at the theoretical level. In the mid ’90s we developed a theory called quantum error correction. It’s about how to encode the quantum state that you’d like to protect in such a clever way that even if there are some interactions with the environment that you can’t control, it still stays robust. At first, that was just kind of a theorist fantasy. It was a little too far ahead of the technology, but 20 years later, the technology is catching up. Now this idea of quantum error correction has become something you could do in the lab.

More here.