Spontaneous emission of atomic systems in the presence of incident fields

TL;DR

This paper investigates how small groups of dipole-coupled two-level atoms emit light spontaneously when illuminated by incident fields, introducing a multi-atom adiabatic passage technique to control emission direction and population transfer.

Contribution

It extends stimulated-Raman-adiabatic-passage (STIRAP) to multi-atom systems and provides analytical expressions for directional emission influenced by incident fields.

Findings

Analytical formulas for emission directionality based on incident fields.

Demonstration of adiabatic population transfer in small atom groups.

Numerical validation of the proposed multi-atom STIRAP method.

Abstract

We characterise the spontaneous emission time and direction from small numbers of dipole-coupled two-level atoms (2LAs) in the presence of incident fields. We show how to use adiabatic passage to admit population transfer between states in the one-quantum subspace for two and three 2LAs. Our method is a multi-atom generalisation of stimulated-Raman-adiabatic-passage (STIRAP) for a single multi-level atom. We use numerical results to justify an ansatz that enables us to give analytical expressions for the directional emission which depends on the incident fields. Our results admit a characterisation of the efficacy of population transfer in small numbers of dipole-coupled 2LAs, and are applicable to proof-of-principle experiments involving dipole-coupled 2LAs.