Articles published in PRL & PRA

Two of our articles have recently been published in APS Journals. The first one, Directional Dicke Subradiance with Nonclassical and Classical Light Sources, has been published in PRL.

Abstract:

We investigate Dicke subradiance of $N\ge 2$ distant quantum sources in free space, i.e., the spatial emission patterns of spontaneously radiating noninteracting multilevel atoms or multiphoton sources, prepared in totally antisymmetric states. We find that the radiated intensity is marked by a full suppression of spontaneous emission in particular directions. In resemblance to the analogous, yet inverted, superradiant emission profiles of $N$ distant two-level atoms prepared in symmetric Dicke states, we call the corresponding emission patterns directional Dicke subradiance. We further derive that higher-order intensity correlations of the light emitted by statistically independent thermal light sources display the same directional Dicke subradiant behavior and show that it stems from the same interference phenomenon as in the case of quantum sources. We finally present measurements of directional Dicke subradiance for $N=2,\dots ,5$ distant thermal light sources corroborating the theoretical findings.

The second article, Phase control of the quantum statistics of collective emission, has been published in PRA.

Abstract:

We report nonclassical aspects of the collective behavior of two atoms in a cavity by investigating the photon statistics and photon distribution over a very broad domain of parameters. Starting with the dynamics of two atoms radiating in phase into the cavity, we study the photon statistics for arbitrary interatomic phases as revealed by the second-order intensity correlation function at zero time, $g^{\left(2\right)}\left(0\right)$, and the Mandel $Q$ parameter. We find that the light field can be tuned from antibunched to (super-)bunched as well as nonclassical to classical behavior by merely modifying the atomic position. The highest nonclassicality in the sense of the smallest $Q$ parameter is found when spontaneous emission, cavity decay, coherent pumping, and atom-cavity coupling are of comparable magnitude. We introduce a quantum version of the negative binomial distribution with its parameters directly related to $Q$ and $g^{\left(2\right)}\left(0\right)$ and discuss its range of applicability. We also examine the Klyshko parameter, which highlights the nonclassicality of the photon distribution.

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