If anyone needs no introduction on a podcast about quantum computing, it's John Preskill. His paper "Quantum Computing in the NISQ era and beyond," published in 2018, is the source of the acronym "NISQ," for Noisy, Intermediate Scale Quantum" computers -- basically everything we are going to build until we get to effective error correction. It's been cited almost 6000 times since, and remains essential reading to this day. John is a particle physicist and professor at Caltech whose central interests are actually cosmology, quantum matter, and quantum gravity -- he sees quantum computing as a powerful means to gain more understanding of the fundamental behavior of our universe. We discuss the information paradox of black holes, quantum error correction, some history of the field, and the work he's doing with his PhD student Robert (Hsin-Yuan) Huang using machine learning to estimate various properties of quantum systems.  How did you become interested in quantum information? 5:13 The discovery of Shor’s algorithm. 10:11 Quantum error correction. 15:51 Black holes and it from qubit. 21:19 Is there a parallel between error correcting codes and holographic projection of three dimensions? 27:27 The difference between theory and experiment in quantum matter. 38:56 Scientific applications of quantum computing. 55:58 Notable links: The Physics of Quantum Information, adapted from John's talk at the Solvay Conference on the Physics of Information Quantum Computing 40 Years Later, an update to John's NISQ paper on the occasion of the 40th anniversary of the conference at Endicott, the Physics of Computation. Lecture notes for John's class on quantum computing at Caltech, PH229 Predicting many properties of a quantum system from very few measurements, one of the papers Robert Huang has published with John, appearing in Nature Physics Tweetables and Quotes: “The idea that you can solve problems efficiently that you'd never be able to solve because it's a quantum world and not a world governed by classical physics, I thought that was one of the coolest ideas I'd ever encountered.” — John Preskill “There's something different about quantum information than ordinary information. You can't look at it without disturbing it.” — John Preskill “Ideas which were being developed without fundamental physics, necessarily in mind, like quantum error correction, have turned out to be very relevant in other areas of physics.” — John Preskill “Thinking about quantum error correction in the context of gravitation led us to construct new types of codes which weren't previously known. “ — John Preskill “With quantum computers and quantum simulators, we can start to investigate new types of matter, new phases, which are far from equilibrium.“ — John Preskill.