Phonon-induced dephasing of chromium colour centres in diamond

TL;DR

This study investigates the coherence and dephasing mechanisms of single photons emitted by chromium colour centres in diamond, highlighting temperature-dependent phonon interactions and their effects on quantum emission efficiency.

Contribution

It provides new insights into phonon-induced dephasing processes and temperature effects on chromium-based colour centres in diamond.

Findings

Dephasing mechanisms are dominated by electron-phonon and phonon-modulated Coulomb interactions.

Zero-phonon linewidth follows a power-law dependence on temperature.

Quantum yield decreases with temperature due to nonradiative channels.

Abstract

We report on the coherence properties of single photons from chromium-based colour centres in diamond. We use field-correlation and spectral lineshape measurements to reveal the interplay between slow spectral wandering and fast dephasing mechanisms as a function of temperature. We show that the zero-phonon transition frequency and its linewidth follow a power-law dependence on temperature indicating that the dominant fast dephasing mechanisms for these centres are direct electron-phonon coupling and phonon-modulated Coulomb coupling to nearby impurities. Further, the observed reduction in the quantum yield for photon emission as a function of temperature is consistent with the opening of additional nonradiative channels through thermal activation to higher energy states predominantly and indicates a near-unity quantum efficiency at 4 K.