The Infrared Absorption Band and Vibronic Structure of the Nitrogen-Vacancy Center in Diamond

TL;DR

This study investigates the phonon modes of the nitrogen-vacancy center in diamond using pump-probe spectroscopy, revealing differences in phonon absorption spectra and identifying a localized high-energy phonon mode, which advances understanding of NV$^-$ properties.

Contribution

The paper provides the first measurement of the phonon sideband of the ${^1}E ightarrow{^1}A_1$ transition in NV$^-$ centers, highlighting differences from previous models and identifying a localized phonon mode.

Findings

The ${^1}E ightarrow{^1}A_1$ phonon absorption spectrum differs from the ${^3}E ightarrow{^3}A_2$ spectrum.

A high-energy 169 meV localized phonon mode of the $^1A_1$ level was identified.

The results challenge existing group-theoretical models of NV$^-$ electronic states.

Abstract

Negatively-charged nitrogen-vacancy (NV$^-$) color centers in diamond have generated much interest for use in quantum technology. Despite the progress made in developing their applications, many questions about the basic properties of NV$^-$ centers remain unresolved. Understanding these properties can validate theoretical models of NV$^-$, improve their use in applications, and support their development into competitive quantum devices. In particular, knowledge of the phonon modes of the $^1A_1$ electronic state is key for understanding the optical pumping process. Using pump-probe spectroscopy, we measured the phonon sideband of the ${^1}E\rightarrow{^1}A_1$ electronic transition in the NV$^-$ center. From this we calculated the ${^1}E\rightarrow{^1}A_1$ one-phonon absorption spectrum and found it to differ from that of the ${^3}E\rightarrow{^3}A_2$ transition, a result which is not anticipated by previous group-theoretical models of the NV$^-$ electronic states. We identified a high-energy 169 meV localized phonon mode of the $^1A_1$ level.