This is a little too simplistic/misleading - yes, QM is linear in terms of states, vector spaces and operators acting on states (its just functional analysis [

This is a little too simplistic/misleading - yes, QM is linear in terms of states, vector spaces and operators acting on states (its just functional analysis [1]) - it’s not linear in terms of how probability distributions and states behave under the action of forces and multi-body interactions (see, eg correlated phenomena like phase transitions, magnetism, superconductivity etc) [1] https://en.m.wikipedia.org/wiki/Functional_analysis https://en.m.wikipedia.org/wiki/Functional_analysis