An operator is a mathematical construct that acts on a wave function to extract the value of a physical observable, such as energy or momentum. In quantum mechanics each measurable quantity has its own operator; the energy operator, for example, is the Hamiltonian. Applying the Hamiltonian to a wave function is the heart of the Schrödinger equation.

算符是作用于波函数以提取某物理可观测量(如能量或动量)数值的数学构造。在量子力学中,每个可测量都有自己的算符;例如,能量算符就是哈密顿算符。把哈密顿算符作用于波函数是薛定谔方程的核心。