Unitarity (physics)
（重定向自Unitarity）
In quantum physics, unitarity is a restriction on the allowed evolution of quantum systems that ensures the sum of probabilities of all possible outcomes of any event is always 1.
More precisely, the operator which describes the progress of a physical system in time must be a unitary operator. When the Hamiltonian is time-independent the unitary operator is ![e^{-i \hat{H} t}](/Images/godic/202502/18/db38d90f9c8593ef97fe9a629e0ff8680204.png")
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