Phase-dependent fluctuations of resonance fluorescence near the coherent population trapping condition

Abstract

We study phase-dependent fluctuations of the resonance fluorescence of a single Λ-type three-level atom in the regime near coherent population trapping, i.e. alongside the two-photon detuning condition. To this end, we employ the method of conditional homodyne detection (CHD) which considers squeezing in the weak driving regime, and extends to non-Gaussian fluctuations for saturating and strong fields. In this framework, and using estimated parameter settings of the resonance fluorescence of a single trapped 138Ba+ ion, the light scattered from the probe transitions is found to manifest a non-classical character and conspicuous asymmetric third-order fluctuations in the amplitude-intensity correlation of CHD.

Quantum interference in the resonance fluorescence of a $J=1/2 - J'=1/2$ atomic system: Quantum beats, nonclassicality, and non-Gaussianity

“…In the present work the fluctuations are mainly third-order ones, due to near and above saturation excitation, and violate classical bounds. We thus explore the phase-dependent fluctuations under conditions of quantum interference following our recent work [20,23,24].…”

“…In several atom-laser systems h π,φ (τ ) has been proven to be time-asymmetric [20,24]. This is not the case with the J = 1/2 → J = 1/2 system so we limit the analysis to positive intervals τ ≥ 0.…”

“…Also, h φ (τ ) is a measure of non-Gaussian fluctuations, here of third-order in the field fluctuations. Resonance fluorescence is a particularly strong case of non-Gaussian noise by being a highly nonlinear stationary nonequilibrium process [20,23,24,27,28], thanks also to its small Hilbert space. This makes resonance fluorescence unsuitable to a quasiprobability distribution approach.…”