Optically driven qubits in artificial molecules

Using coupled quantum dots in which a qubit is regarded as the superposition of ground states in each dot, the models of quantum gates molecules were derived. Time-dependent Schrodinger equation was used to prove that simple artificial molecules associated with light pulses serve as the quantum gates. The decoherence of a quantum state during the unitary operation was analyzed by calculating the relaxation rate by phonon process. The results showed that the number of quantum states in the quantum dot depends on the confinement potential or the radius of the quantum dot.