waves classical physics quantum states solutions Schrödinger equation linear linear combination
Mathematically, much like waves in classical physics, any two (or more) quantum states can be added together ("superposed") and the result will be another valid quantum state; conversely, every quantum state can be represented as a sum of two or more other distinct states. Mathematically, it refers to a property of solutions to the Schrödinger equation: since the Schrödinger equation is linear, any linear combination of solutions will also be a solution(s).
