Coherent perfect absorption in deeply subwavelength films in the single photon regime

TL;DR

This paper demonstrates the deterministic coherent absorption of single photons in deeply subwavelength films, advancing control over light-matter interactions at the quantum level for applications in sensing and photonic technologies.

Contribution

It introduces a method for achieving near-unity probability of single-photon absorption in subwavelength films using standing wave configurations, extending coherent absorption to the quantum regime.

Findings

Deterministic single-photon absorption in subwavelength films.

Nearly unitary coupling probability into localized plasmon modes.

Enhanced understanding of quantum coherent absorption processes.

Abstract

The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis depend on the absorption of light and novel approaches such as coherent absorption from a standing wave promise total dissipation of energy. Extending the control of absorption down to very low light levels and eventually to the single photon regime is of great interest yet remains largely unexplored. Here we demonstrate the coherent absorption of single photons in a deeply sub-wavelength 50% absorber. We show that while absorption of photons from a travelling wave is probabilistic, standing wave absorption can be observed deterministically, with nearly unitary probability of coupling a photon into a mode of the material, e.g. a localised plasmon when this is a metamaterial excited at the plasmon resonance. These results bring a better understanding of the coherent absorption process, which is of central importance for light harvesting, detection, sensing and photonic data processing applications.