# Near-unity quantum yield from carbon nanotube excitons coupled to plasmonic nanocavities

## TL;DR

This paper demonstrates that coupling single-walled carbon nanotube excitons to plasmonic nanocavities significantly enhances their quantum yield and photon emission rate, enabling applications in quantum light sources and nanoscale thermometry.

## Contribution

It reports the first achievement of near-unity quantum yield and high Purcell factors in SWCNTs coupled to plasmonic nanocavities, surpassing previous low-yield limitations.

## Key findings

- Quantum yield increased to 70% with nanocavity coupling.
- Photon emission rate reached 1.7 MHz into the first lens.
- Nanocavity-coupled SWCNTs can detect nanoscale heat changes.

## Abstract

Single-walled carbon nanotubes (SWCNTs) are promising absorbers and emitters to enable novel photonic and optoelectronic applications but are also known to severely suffer from low optical quantum yields. Here we demonstrate SWCNTs excitons coupled to plasmonic nanocavities reaching deeply into the Purcell regime with FP=234 (average FP=76), near unity quantum yields of 70% (average 41%), and a photon emission rate of 1.7 MHz into the first lens. The measured ultra-narrow exciton linewidth (18 micro eV) implies furthermore generation of indistinguishable single photons from a SWCNT. To demonstrate utility beyond quantum light sources we show that nanocavity-coupled SWCNTs perform as single-molecule thermometers detecting plasmonically induced heat (Delta T=150K) in a unique interplay of excitons, phonons, and plasmons at the nanoscale.

---
Source: https://tomesphere.com/paper/1705.02034