Information in a quantum cellular automata architecture is encoded in the p
olarization 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 hav
e shown that a quantum constriction electrostatically coupled to the quantu
m 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 s
ensitivity. (C) 1998 Elsevier Science S.A. All rights reserved.