Part VIII — Quantum Complexity
You have now seen the algorithms — Deutsch, Grover, Shor, QFT, phase estimation. Before we turn to why hardware is hard, we owe the theoretical foundations an honest chapter: what complexity theory actually claims about quantum computers, what it does not, and where speedups genuinely come from. This is the part that protects you from the two symmetrical diseases of the field: hype ("quantum computers solve everything exponentially faster") and dismissiveness ("just parallel universes guessing"). Both die on contact with the material below.