Quantum dot circuit and a method of characterizing such a circuit

Abstract

Quantum dot circuit and a method of characterizing such a circuit Voltages that enable control of electron occupation in a series of quantum dots are determined by a method of measuring effects of gate electrode voltages on a quantum dot circuit. The quantum dot circuit comprises a channel (), first gate electrodes (-) that extend over locations along the edge of the channel to create potentials barriers defining the potentials well therebetween, as well as second gate electrodes (-) adjacent to potential wells, for controlling depths of the successive electrical potential wells between the potential barriers. First, channel currents are measured in a pre-scan of bias voltages of the first gates for controlling the potential barriers. The result is used to set their bias levels in, a scan over a two-dimensional range of combinations of bias voltages on the second gates for controlling the depths. In this scan an indication of charge carrier occupation of potential wells at consecutive positions along the channel such as electromagnetic wave reflection is measured. Pattern matching with a pattern of crossing occupation edges is applied to the result. This involves a two-dimensional image that has the combinations of the bias voltages as image points and the indication of charge carrier occupation as image values. The pattern matching detects an image point where the image matches a pattern of crossing edges along predetermined directions.