The bi-directional electron pump operated in the double dot regime

We describe the electrical characteristics of a bi-directional electron pump. The pump consists of two multiple tunnel junction Coulomb blockade devices in series. The two devices are separated by a macroscopic island to which one sinusoidal radio-frequency signal is applied. One multiple tunnel junction was operated in the single-dot regime, while the other one was set at the transition from the single-dot to the double-dot regime. We show that the dc characteristic of both Coulomb blockade devices is faithfully transferred to the ac characteristic. An effect of the double-dot regime is to alter the periodicity of the pump-current oscillations. © 2004 Elsevier B.V. All rights reserved.