Chapter 9: New Approach to Quantum Amplification by Superradiant Emission of Radiation
We report a new analytical solution of a two–level system driven by an arbitrary time–dependent electromagnetic pulse. The new solution goes beyond the rotating wave approximation (RWA), and is governed by the complex pulse area and the time–dependent Stark shift phase. The present work is motivated by a new concept of the quantum amplification by superradiant emission of radiation (QASER). The original QASER mechanism was suppressed by the Stark effect induced by the strong off–resonant driving field. Furthermore the QASER description was based on the Rabi solution for a driven two–level system derived for a square driving pulse in the RWA. The present approach, based on a new solution for a driven two–level system, is valid for a general time–dependent field beyond the RWA. With a two–mode driving field that is detuned above and below the atomic transition frequency by the same amount Δ we achieve cancellation of the induced Stark shift. In this way we secure parametric excitation of a driven two–level atomic media without a time–dependent Stark shift.