Universal Quantum Logic Gates Based on Phase Control

Based on the semi-classical theory of the interaction between light and matter, we propose an effective scheme for describing the realization of single quantum gates. The rigorous analytical solution for the resonant system, in which the double ultra-short powerful laser pulses with accurately controllable relative phase difference will interact with the atoms, is obtained by solving the time-dependent Schrödinger equation. According to the corresponding solution, we deduce the systematic matrix expression of unitary transformation. Universal quantum logic gates are all implemented theoretically by means of regulating properly the laser pulses´ intensity and its relative phase difference as well as the optic detuning. This method also proves practical in terms of its comparably easier manipulation.