Question

Time evolution operator is an example of ... Operator.

Answer 1

Answer:

We define the time evolution operator U(t, t0): |α, t0; t〉 = U(t, t0)|α, t0〉, which must satisfy physically relevant conditions. ... In other words, the normalization of the states does not depend on time: 〈α, t0|α, t0〉 = 〈α, t0; t|α, t0; t〉 = 〈α, t0|U†(t, t0)U(t, t0)|α, t0〉.