Tuning Fano-type resonances in coupled quantum point contacts by applying asymmetric voltages

We study the ballistic magnetotransport in a double quantum point contact (QPC) device consisting of a quasi-one-dimensional quantum wire with an embedded islandlike impurity-etched nanohole as in a recently published experiment {J. C. Chen et al., [Appl. Phys. Lett. 94, 012105 (2009)]}. We reproduce the zero field quantized conductance, the interference phenomenon induced by the coupled QPCs, as well as the Ramsauer-like resonances observed in the experiments. At finite magnetic fields Fano-type resonances arises in the conductance due to the formation of localized states at the impurity periphery and to an interedge state resonant coupling effect. It is predicted that the Fano-type resonances can be controlled by an asymmetric confinement of the QPCs. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3579538]