A spin pump turnstile: parametric pumping of a spin-polarized current through a nearly-closed quantum dot

摘要

We investigate parametric pumping of a spin-polarized current through anearly-closed quantum dot in a perpendicular magnetic field. Pumping isachieved by tuning the tunnel couplings to the left and right lead - therebyoperating the quantum dot as a turnstile - and changing either the magneticfield or a gate-voltage. We analyze the quantum dynamics of a pumping cycle andthe limiting time scales for operating the quantum dot turnstile as a pure spinpump. The proposed device can be used as a fully controllable double-sided andbipolar spin filter and to inject spins "on demand".