TUNNELING TIME AND ENERGY UNCERTAINTY OF SURFACE-STATE ELECTRONS

We show that the tunneling time-tau of a localized electron tunneling through a barrier modulated by a microwave field satisfies the relation DELTA-E(tau) = HBAR, where the uncertainty DELTA-E in the energy of the coupled electron-field system is determined by the response of the electron to the time-dependent fields. We express DELTA-E as the expectation value of an operator and point out how it can be measured experimentally.