Temporally correlated transport and shot noise suppression in a ballistic quantum point contact

Abstract

Wide-band shot noise, associated with DC current flow through a quantum point contact (QPC), is measured in the microwave frequency range 8–18 GHz. As the number of conducting channels in the QPC changes, the noise power oscillates, with a value of almost zero at the conductance plateaux. Consistent with existing theories, the noise peaks depend linearly on the DC current. Surprisingly, however, in the pinch-off region, where QPC is expected to behave as a classical injector, we find strong noise suppression, possibly mediated by the Coulomb interaction in the QPC region.