Highly directional photon superbunching from a 'few atom' chain of emitters

TL;DR

This paper investigates how a linear chain of identical atoms can produce highly directional, correlated photon pairs with superbunching, influenced by selective excitation and atomic arrangement, revealing new control over photon emission patterns.

Contribution

It demonstrates the control of photon pair directionality and superbunching through selective excitation and atomic positioning in a linear chain, a novel approach in quantum light sources.

Findings

Directional photon pair emission can be controlled by excitation position.

Superbunching increases with the number of atoms in the chain.

Photon correlations are highly concentrated in specific directions.

Abstract

We examine angular distribution of the probability of correlated fluorescence photon emission from a linear chain of identical equidistant two-level atoms. We selectively excite one of the atoms by a resonant laser field. The atoms are coupled to each other via the dipole-dipole interaction and collective spontaneous emission. Our attention is focused on the simultaneous observation of correlated pairs of photons. It is found that the interference between the emitting atoms can result in a highly directional emission of photon pairs. These pairs of photons posses strong correlations and their emission is highly concentrated into specific detection directions. We demonstrate the crucial role of the selective coherent excitation in such a geometrical configuration. Shifting the driving field from an atom located at one end of the chain to the other causes the radiation pattern to flip to the opposite half of the detection plane. Furthermore, we find that atomic systems in which only an atom situated at a particular position within the linear chain is driven by a laser field can radiate correlated twin photons in directions along which the radiation of single photons is significantly reduced. Alternatively, superbunching in the emitted photon statistics preferentially occurs in directions of negligible or vanishing single photon emission. The effect of superbunching strengthens as more emitters are added to the chain. Depending on the number of atoms and the position of the driven atom within the chain, the strongly correlated pairs of photons can be emitted into well-defined single, two or four directions.