Detection of charge states in nanowire quantum dots using a quantum point contact

The authors demonstrate operation of a charge readout scheme for quantum dots in a semiconductor nanowire using a quantum point contact defined in a GaAs/AlGaAs two-dimensional electron gas beneath the nanowire. The quantum dots were fabricated by epitaxial growth of InP barriers along a n-type InAs nanowire. Applying negative voltages to two split-gate electrodes aligned to the nanowire induces a quantum point contact in the two-dimensional electron gas such that charging of quantum dots in the nanowire modulates the quantum point contact transmission, thus resulting in the desired detector response. (c) 2007 American Institute of Physics.