The paper reports a derived kinetic equation describing the dynamics of an atomic localized ensemble in a broadband squeezed light field taking into account second-order effects in the constant of interaction of atoms with the field (Stark interaction). Traditionally in deriving  the kinetic equation for an open system, effects of this kind are usually ignored, but due to the established specific properties  they are considered as being "built in" and tend to renormalize  the terms of the kinetic equation determined by first-order effects.

The kinetic equation is derived by applying algebraic resonance perturbation theory, which defines the creating, annihilating, and counting process for a quantum stochastic differential equation. For this purpose, the Stark interaction operator of a system with a broadband quantized electromagnetic field with a nonzero photon density is represented as a quantum counting process at the stage of formation of the electromagnetic field concerned. The equation differs from the known ones, but appears to agree with them in particular and limiting cases.

Stark interaction manifests itself in a change in the shape of the superradiance pulse of an atomic ensemble in the Dicke state and additional shifts in the energy levels of the atom. The figure shows graphs of superradiance pulses for ensembles in the Dicke state with the same value of the number of atoms under conditions of Stark interaction with squeezed light (red graph), neglect of Stark interaction with squeezed light (blue graph), and ensemble radiation into vacuum (green graph).

Trubilko A.I. and Basharov A.M.
JETP Letters 122, issue 1 (2025)