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.