Detecting a true quantum pump effect

Even though quantum pumping is a very promising field, it has unfortunately not been unambiguously experimentally detected. The reason being that in the experiments the rectification effect overshadows the pumped current. One of the better known ways to detect it is by using the magnetic field symmetry properties of the rectified and pumped currents. The rectified currents are symmetric with respect to magnetic field reversal while the pumped currents do not possess any definite symmetry with respect to field reversal. This feature has been exploited in some recent works. In this work we look beyond this magnetic field symmetry properties and provide examples wherein the nature or magnitudes of the pumped and rectified currents are exactly opposite enabling an effective distinction between the two. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006