Model and logic gates for quantum computing with a two-level system in a resonant-frequency field

摘要

A model describing the evolution of a two-level quantum system under the continuous measurement of the dipole moment is proposed. The action of the instrument is allowed for by including the measured data into the evolution equation in a self-consistent manner, subject to a certain criterion of motion. It is predicted that the superposition persistence time will increase if the measurement is carried out with a low accuracy and a minimum variance. Within this framework, a novel concept of the quantum logic gate is presented, the logic operations being performed by varying the rate of energy-level transitions.