Ultranarrow Bright Single-Photon Emitters in Diamond with Strong Broadband Phonon Decoupling

TL;DR

This paper reports the discovery of ultranarrow, bright single-photon emitters in diamond nanocrystals that are strongly decoupled from bulk phonons, leading to enhanced coherence and potential quantum technology applications.

Contribution

It introduces a new type of color center in nanodiamonds with unprecedented phonon decoupling and narrow linewidths at room temperature, advancing quantum emitter performance.

Findings

Record-narrow linewidths down to 0.3 nm at room temperature

Suppressed bulk phonon sideband indicating strong phonon decoupling

Bright emission exceeding 10 million counts per second

Abstract

Single-photon emitters are fundamental building blocks for quantum information processing, communication and sensing. However, unwanted interactions with bulk phonons in their host environment strongly limit their coherence and controllability. We report single color centers in nanodiamonds that are strongly and comprehensively decoupled from the bulk phononic environment. The color centers feature record-narrow linewidths down to 0.3 nm at room temperature and stable, bright emission, exceeding 10 Mcps in saturation. Notably, the bulk phonon sideband is almost entirely suppressed, revealing the presence of a single localized vibrational mode outside the diamond phonon band. Our observations and simulations point towards a unique mechanism for phonon decoupling in common wide-gap materials, based on a strongly radiative orbital transition coupled to a localized vibrational mode. The new color center enables qualitatively higher performance for applications in quantum networks and nanoscale sensing, and the exploration of new physical resources associated with vibrational states.