Atomic Pair Interactions Control Light Scattering and Absorption Efficiency.

The interaction of light with matter at the atomic scale reveals complex phenomena dependent on both the properties of the light and the configuration of the atoms themselves. Understanding these interactions is crucial for developing technologies reliant on precise control of light-matter coupling, such as advanced optical computing and quantum information processing. Researchers at the Universidad de Valladolid, specifically L. Acevedo, J. Sánchez-Cánovas, and M. Donaire, investigate this interplay in a recent study concerning the optical response of a binary atomic system subject to incoherent excitation. Their work, titled ‘Optical response of a binary atomic system with incoherent gain’, details how the scattering, absorption, and emission of photons are affected by the distance between two atoms and the rate at which they are excited, demonstrating the potential to manipulate these properties for future applications.

The interaction of light with pairs of identical atoms receives detailed scrutiny, specifically concerning how incoherent pumping influences their collective response. Researchers demonstrate the ability to tailor photon scattering, absorption, stimulated and spontaneous emission, and resonant energy transfer through manipulation of both interatomic distance and pump rate. The study establishes that strong pumping effectively compensates for optical losses, leading to a substantial reduction in the collective extinction cross-section, irrespective of the distance separating the atoms.

Researchers meticulously characterise photon scattering, absorption, emission, and the temporal evolution of the atomic system, demonstrating how these processes are manipulated through adjustments to interatomic distance and pump rate. They employ a diagrammatic formalism, building upon previous work by Donaire (2021), to model these interactions and reveal nuanced control over the system’s optical properties, offering a robust framework for understanding complex phenomena. The extinction cross-section represents the effective area an object presents to incoming radiation, quantifying how strongly it absorbs or scatters light.

The findings demonstrate that strong pumping effectively compensates for losses within the system, leading to a negligible collective extinction cross-section irrespective of the distance separating the atoms. This compensation results in a substantial reduction – to less than half – of the total extinction cross-section compared to a scenario without pumping, highlighting the potential for precise control over optical properties. Conversely, weak pumping combined with short interatomic distances induces significant interference effects, suppressing the extinction cross-section relative to that observed in isolated atoms, revealing a nuanced interplay between gain, loss, and interference.

The study highlights the critical role of both pump rate and interatomic distance in tailoring the optical behaviour of the binary system, achieving precise control over the extinction cross-section and effectively modulating the system’s interaction with light. The observed suppression of the extinction cross-section under specific conditions suggests potential applications in manipulating light-matter interactions and controlling optical properties at the nanoscale, opening possibilities for creating highly sensitive sensors, efficient light sources, and novel quantum communication protocols. Further investigation into the scaling of these effects to larger atomic ensembles proves crucial for realising practical applications.

Researchers successfully employ a diagrammatic formalism to characterise these phenomena, providing a robust framework for understanding the complex interplay of optical processes within the binary atomic system, and allowing for a detailed analysis of how different excitation and emission pathways contribute to the overall response. This detailed analysis enables the prediction and control of system behaviour, contributing to a growing body of knowledge concerning the manipulation of light-matter interactions and offering insights into the development of novel optical technologies. Future research directions focus on exploiting these control mechanisms for applications in quantum information processing and the development of advanced optical devices.