Theory of Spin Relaxation in Laterally Coupled Quantum Dots

The electron’s spin is a natural two-level system. It can be aligned parallel or antiparallel to an external magnetic field, with a certain energy difference between both system states. In the context of quantum information processing, those two spin orientations can be used to define the states of a qubit–a quantum mechanical two-level system with a complete set of manipulations and the requirement of tunable coupling to other qubits. However, an excited spin state may eventually relax into the ground state, and hereby lose its stored information. Knowing and understanding the mechanism of spin relaxation is crucial for the implementation of a spin-based quantum computer.