Simulation of a non-invasive charge detector for quantum cellular automata

TL;DR

This paper presents a numerical simulation of a non-invasive charge detector using a quantum point contact coupled to a quantum dot, aiming to improve quantum cellular automata readout methods.

Contribution

It introduces a detailed simulation approach for optimizing a quantum charge detector based on a quantum point contact near a quantum dot.

Findings

Computed occupancy and resistance as functions of gate voltage

Derived design criteria for maximum sensitivity

Validated the feasibility of the proposed detection scheme

Abstract

Information in a Quantum Cellular Automata architecture is encoded in the polarizazion state of a cell, i.e., in the occupation numbers of the quantum dots of which the cell is made up. Non-invasive charge detectors of single electrons in a quantum dot are therefore needed, and recent experiments have shown that a quantum constriction electrostatically coupled to the quantum dot may be a viable solution. We have performed a numerical simulation of a system made of a quantum dot and a nearby quantum point contact defined, by means of depleting metal gates, in a two-dimensional electron gas at a GaAs/AlGaAs heterointerface. We have computed the occupancy of each dot and the resistance of the quantum wire as a function of the voltage applied to the plunger gate, and have derived design criteria for achieving optimal sensitivity.