Part XIII — Quantum Applications
Algorithms in the abstract are one thing; applications that survive contact with data, noise, and economics are another. This part examines the five application families with real momentum — simulation, chemistry, variational methods, machine learning, cryptography — with the honesty each deserves: some are roadmap bets (simulation, chemistry at fault-tolerant scale), some are contested (variational, QML), and one is already deployed at civilizational scale (cryptography — as defense). Throughout, the method is the same: for every claimed application, ask who pays, for what precision, against which classical baseline.