Physics · Quantum Mechanics

Two operators A and B satisfy the commutation relations [H, A] = -ħωB and [H, B] = ħωA, where ω is a constant and H is the Hamiltonian of the system. The expectation value ⟨A⟩ψ(t) = ⟨ψ|A|ψ⟩ in a state |ψ⟩ such that at time t = 0, ⟨A⟩ψ(0) = 0 and ⟨B⟩ψ(0) = 1, is: