Adiabaticity in the Hamiltonian functional integral (Q1210327)

We describe an alternative view of the adiabatic theorem suggested by the Hamiltonian functional integral. The adiabatic limit is achieved by phase cancellations in the transitions between the states of the system and is not due to the measure of the functional integral having support only on the trivial path. We illustrate this using a general \(2 \times 2\) time- dependent Hamiltonian and also describe Berry's phase in this formalism.