Optical addressing of an individual erbium ion in silicon

TL;DR

This paper demonstrates a hybrid optical-electrical method to detect the spin state of a single erbium ion in silicon, overcoming thermal and photon collection limitations for quantum information applications.

Contribution

It introduces a novel hybrid approach combining optical excitation and electrical charge sensing for single defect spin detection in silicon.

Findings

Optical excitation changes the charge state conditional on spin.

Electrical detection of optical excitation is achieved at the single-site level.

Method overcomes thermal broadening and photon collection challenges.

Abstract

The detection of electron spins associated with single defects in solids is a critical operation for a range of quantum information and measurement applications currently under development. To date, it has only been accomplished for two centres in crystalline solids: phosphorus in silicon using electrical readout based on a single electron transistor (SET) and nitrogen-vacancy centres in diamond using optical readout. A spin readout fidelity of about 90% has been demonstrated with both electrical readout and optical readout, however, the thermal limitations of the electrical readout and the poor photon collection efficiency of the optical readout hinder achieving the high fidelity required for quantum information applications. Here we demonstrate a hybrid approach using optical excitation to change the charge state of the defect centre in a silicon-based SET, conditional on its spin state, and then detecting this change electrically. The optical frequency addressing in high spectral resolution conquers the thermal broadening limitation of the previous electrical readout and charge sensing avoids the difficulties of efficient photon collection. This is done with erbium in silicon and has the potential to enable new architectures for quantum information processing devices and to dramatically increase the range of defect centres that can be exploited. Further, the efficient electrical detection of the optical excitation of single sites in silicon is a major step in developing an interconnect between silicon and optical based quantum computing technologies.