One-dimensional two-barrier quantum pump with harmonically oscillating barriers: Perturbative, strong-signal, and nonadiabatic regimes

We study the stationary current in a one-dimensional quantum pump composed of two harmonically oscillating delta-functional barriers (wells). The harmonic signals are applied to any or both barriers. The low-signal and nonlinear regimes are considered. The former case is studied by the theory of perturbation, while the nonlinear regime is studied numerically. The numerical, perturbative, and adiabatic results are compared with each other. It is found that the current has peculiarities, caused by stationary and quasistationary electron states as well as threshold singularities. The direction and value of the current depend on the frequency, the Fermi momentum, the values of the stationary and alternating voltages, and the phase shift between them. In the case of a strong applied signal the stationary current exhibits multiphoton oscillations.