The time derivative of a quantum state is - i H ^ ^ / ℏ ℏ (by Schrödinger equation). Equivalently, since the operators are not explicitly time-dependent, they can be seen to be evolving in time (see Heisenberg picture) according to their commutation relation with the Hamiltonian: d Q ^ ^ d t = i ℏ ℏ [ H ^ ^ , Q ^ ^ ] d P ^ ^ d t = i ℏ ℏ [ H ^ ^ , P ^ ^ ] .