Spectral broadening of a single Er$^{3+}$ ion in a Si nano-transistor

TL;DR

This study investigates the spectral broadening mechanisms of a single Er$^{3+}$ ion in a silicon nano-transistor, revealing that spectral diffusion at high optical powers causes linewidth increases, impacting quantum applications.

Contribution

It provides the first detailed analysis of spectral broadening in a single Er$^{3+}$ ion within a silicon nano-transistor, highlighting the role of spectral diffusion at high optical powers.

Findings

Spectral broadening occurs at high optical powers.

Spectral diffusion causes linewidth increases.

Lorentzian lineshape persists across optical powers.

Abstract

Single rare-earth ions in solids show great potential for quantum applications, including single photon emission, quantum computing, and high-precision sensing. However, homogeneous linewidths observed for single rare-earth ions are orders of magnitude larger than the sub-kilohertz linewidths observed for ensembles in bulk crystals. The spectral broadening creates a significant challenge for achieving entanglement generation and qubit operation with single rare-earth ions, so it is critical to investigate the broadening mechanisms. We report a spectral broadening study on a single Er$^{3+}$ ion in a Si nano-transistor. The Er-induced photoionisation rate is found to be an appropriate quantity to represent the optical transition probability for spectroscopic studies, and the single ion spectra display a Lorentzian lineshape at all optical powers in use. Spectral broadening is observed at relatively high optical powers and is caused by spectral diffusion on a fast time scale.