Efficient frequency-selective single-photon antennas based on a bio-inspired nano-scale atomic ring design with 9-fold symmetry

TL;DR

This paper presents a bio-inspired nano-scale atomic ring design with 9-fold symmetry that acts as an efficient, tunable single-photon antenna, leveraging collective quantum effects to optimize absorption and energy transport.

Contribution

It introduces a novel ring-based antenna structure inspired by biological complexes, demonstrating enhanced absorption and tunability through geometric and symmetry considerations.

Findings

Optimal absorption occurs with nine emitters in a nonagon configuration.

The structure achieves a maximum absorption cross-section surpassing single emitters.

Dark collective eigenstates facilitate efficient energy absorption and fast transport.

Abstract

Quantum emitters in confined arrays exhibit geometry dependent collective dynamics. In particular, nanoscopic regular polygon-shaped arrays can possess sub-radiant states with an exciton lifetime growing exponentially with emitter number. We show that by placing an extra resonant absorptive dipole at the ring center, such a structure becomes a highly efficient single-photon absorber with tailorable frequency. Interestingly, for exactly nine emitters in a nonagon, as it appears in a common biological light-harvesting complex (LHC2), we find a distinct minimum for its most dark state decay rate and a maximum of the effective absorption cross-section, surpassing that for a single absorptive emitter. The origin of this optimum for nine emitters can be geometrically traced to the fact that the sum of coupling strengths of a single ring emitter to all others including the center ring closely matches the coupling of the center to all ring emitters. The emerging dark collective eigenstate has dominant center occupation facilitating efficient energy absorption and fast transport. The resonance frequency can be tuned via ring size and dipole polarization. In analogy to parabolic antennas, the ring concentrates the incoming radiation at the center without being significantly excited, which minimizes transport loss and time.