Introduction to Quantum Mechanics 2

Appendix 2Quantum Dot of Semiconductor Materials

A2.1. Definition, qubits

A quantum dot is a heterostructure obtained by 0D confinement of semiconductor materials. Current research on the properties of quantum dots is motivated by the fact that they constitute potential elementary bricks of the quantum processing of information, known as quantum bits or qubits. On a long term, it may be possible to use the properties of quantum dots at a nanometric scale in order to get an infinitely more rapid coding and processing of information.

The unit in classical computer science is the bit, which follows a binary logic. It takes only two values denoted as 0 or 1. On the other hand, a quantum bit is associated with the quantum state of a quantum dot assimilated with a system with two levels characterized by the states |0〉 and |1〉. Any linear superposition |Φ〉 of these two states is also a state materializing the quantum bit with:

[A2.1]

The existence of superpositions of type [A2.1] makes it possible to develop quantum computers that are far more rapid than a classical computer.

A2.2. Quantum dots emergence

Many quantum dots are generated by interface defects of the quantum wires such as those engraved in V. This is particularly the case of the quantum wires of gallium arsenide (GaAs) that are used as quantum wells, and of the alloy of gallium arsenide and aluminum (GaAlAs), which ...