Identification of a telecom wavelength single photon emitter in silicon

TL;DR

This paper identifies the microscopic structure of a silicon defect that acts as a single photon emitter at telecommunication wavelengths, using first-principles calculations to explain its optical properties and potential as a qubit.

Contribution

The study provides the first detailed atomic-level identification of the defect responsible for telecom wavelength single photon emission in silicon, combining advanced computational methods.

Findings

The defect is a C_s C_i carbon impurity complex in silicon.

The optical signals originate from athermal rotational reorientation of the defect.

The defect exhibits reduced tunneling rate at low temperatures, explaining magnetic resonance observations.

Abstract

We identify the exact microscopic structure of the G photoluminescence center in silicon by first principles calculations with including a self-consistent many-body perturbation method, which is a telecommunication wavelength single photon source. The defect constitutes of $\text{C}_\text{s}\text{C}_\text{i}$ carbon impurities in its $\text{C}_\text{s}-\text{Si}_\text{i}-\text{C}_\text{s}$ configuration in the neutral charge state, where $s$ and $i$ stand for the respective substitutional and interstitial positions in the Si lattice. We reveal that the observed fine structure of its optical signals originates from the athermal rotational reorientation of the defect. We attribute the monoclinic symmetry reported in optically detected magnetic resonance measurements to the reduced tunneling rate at very low temperatures. We discuss the thermally activated motional averaging of the defect properties and the nature of the qubit state.