Physical Review A
Berry phase and nonstationarity of a quantum state
J. Y. Zeng, Yian Lei
Abstract
The intimate connection between the Berry phase and the nonstationarity of a quantum state is discussed. For a quantum system with time-independent Hamiltonian $H$, there may exist stationary states. It is shown that for a stationary state, the Berry phase always vanishes, and only for a nonstationary state after a cyclic evolution might the Berry phase appear. For time-dependent $H$, there exists no exactly stationary state, hence the Berry phase may appear.