"Just as it took decades for us to get supercomputers in our pockets, it will take decades to work through all the engineering problems necessary to build large

"Just as it took decades for us to get supercomputers in our pockets, it will take decades to work through all the engineering problems necessary to build large-enough quantum computers." This is not an accurate analogy, and you shouldn't believe that there is a continuous engineering path to practical quantum computing as there was for miniaturization of semiconductors. We understood that there was "plenty of room at the bottom" for semiconductors and classical computation and had "Moore's Law" which pointed to a future with supercomputers in our pocket. However the physics of quantum computation are not so well bounded today, and the author acknowledges that we may not be able to build such quantum computers, and he is placing a bet. Let me place my bet: error correction will prove intractable for quantum computation, with a recursive relationship between the size and coherence time of a topological qubit, such that the minimum number of particles required to factor N-bit numbers will exceed the number of particles in the universe for an N that is small enough to just keep using RSA on classical computers.