Theory for Quantum Interference Signal from an Inhomogeneously Broadened Two-Level System Excited by an Optically...

A useful expression for the quantum interference (QI) signal was derived for an inhomogeneously broadened two-level system when it was excited by an optically phase-controlled laser-pulse pair. It was shown that the QI signal oscillates as a function of a relative optical phase, with the reduced angular frequency given by the relation ωa = (Γ(2)ω0 + γg(2)Ω)/(γg(2) + Γ(2)), where γg and Γ are standard deviations of the system's absorption and the laser spectra both having a Gaussian line shape, respectively, and ω0 and Ω are the center angular frequency of the system absorption and the carrier angular frequency of the laser, respectively.