Wednesday, 2 August 2017

quantum mechanics - Heisenberg equation with time-dependent Hamiltonian


It is the root of quantum mechanics that Heisenberg picture and Schrödinger picture are equivalent?


In most textbooks and wikipedia, the equivalence is proved with a time-independent Hamiltonian. However, some literature uses Heisenberg equation with time-dependent Hamiltonian.


$$i\hbar \frac{dA}{dt}~=~[A(t),H(t)]+i\hbar \frac{\partial A}{\partial t}.$$


So, does Heisenberg equation work with time-dependent Hamiltonian? If so, any proof?



Answer



OK, I figured it out myself. Heisenberg equation still holds for time-dependent Hamiltonians:


$$i\hbar \frac{dA}{dt}~=~[A(t),H(t)]+i\hbar \frac{\partial A}{\partial t}.$$



However, now $H(t)$ is defined as $U^\dagger(t)H_S(t)U(t)$.


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