Quantum dots: Applications in technology and in quantum physics

The description of a quantum dot can be applied to a great variety of structures, and their application has become important in a wide range of technical fields, for both optical and electronics applications. One of the earliest gate-defined lateral quantum dots was fabricated on a GaAs/AlGaAs heterojunction, in which a quasi-two-dimensional electron gas is formed on the GaAs side of the hetero-interface. We now know that these open dots remain quantum objects, a result that is useful if they are to be incorporated in any new type of information processing, such as has been suggested for quantum computation. Indeed, it is clear that a few robust states exist in these open dots, and that these states will lead to a signature of each dot through a set of reproducible "fluctuations" as the gate voltage, or a magnetic field is varied. These robust states provide a set of discrete pointer states, which govern the quantum to classical transition, and they are uncoupled from dots nearby in energy through the decoherence process.