Quantum-enhanced capture of photons using optical ratchet states

TL;DR

This paper introduces optical ratchet states in ring-like light-harvesting systems, enabling enhanced photon absorption and power output by preventing exciton re-emission, inspired by photosynthetic structures.

Contribution

It proposes a novel class of states called ratchets that improve photon capture efficiency in light-harvesting systems, demonstrating significant power enhancement through simulations.

Findings

Peak power enhancement up to 35 times under ambient conditions.

Power enhancement exceeds 20% in slow extraction limit.

Ratchet states effectively prevent exciton re-emission, increasing photon absorption.

Abstract

Natural and artificial light harvesting systems often operate in a regime where the flux of photons is relatively low. Besides absorbing as many photons as possible it is therefore paramount to prevent excitons from annihilation via photon re-emission until they have undergone an irreversible energy conversion process. Taking inspiration from photosynthetic antenna structures, we here consider ring-like systems and introduce a class of states we call ratchets: excited states capable of absorbing but not emitting light. This allows our antennae to absorb further photons whilst retaining the excitations from those that have already been captured. Simulations for a ring of four sites reveal a peak power enhancement by up to a factor of 35 under ambient conditions owing to a combination of ratcheting and the prevention of emission through dark-state population. In the slow extraction limit the achievable power enhancement due to ratcheting alone exceeds 20%.