Tunable two-electron spin states in quantum dot structures and the applicability for making spin qubits

The electronic configuration in a quantum dot is determined in such a way as to minimize the total energy associated with the quantum mechanical and interaction effects. The spin configuration is tunable with various parameters such as number of electrons, strength of confinement and magnetic field, and this provides a good potential for applications to quantum computing and spintronics. In this paper we review the experiments conducted to characterize the electronic properties of the two-electron spin states, such as the tunability of singlet and triplet states, the time scale for spin relaxation, and the modulation of exchange coupling, which are vital for making spin qubits.