Single site optical spectroscopy of coupled Er3+ ion pairs in silicon

Individual optical emitters coupled via coherent interactions are attractive qubits for quantum communications applications. Here, we present the first study of single pairs of interacting rare earth ions and determine the interactions between ions in the pair with high resolution. We identify two examples of Er3+ pair sites in Er implanted Si and characterise the interactions using optical Zeeman spectroscopy. We identify one pair as two Er3+ ions in sites of at least C-2 symmetry coupled via a large, 200 GHz, Ising-like spin interaction in both optical ground and excited states. The high measurement resolution allows non-Ising contributions to the interaction of <1% to be observed, attributed to site distortion. By bringing two optical transitions into resonance with a magnetic field, we observe a 0.8 GHz optical interaction of unusual magnetic-dipole/electric-dipole character with strong polarization selection rules. We discuss the use of this type of strongly coupled, field-tunable rare earth pair system for quantum processing.

Automated summary

This study examines the interactions of single pairs of rare earth ions, identifying high-resolution interactions and unusual optical interactions. By characterizing the Er3+ pair sites using optical Zeeman spectroscopy, the researchers observe a large Ising-like spin interaction and a unique magnetic-dipole/electric-dipole optical interaction, indicating potential applications for quantum processing with field-tunable rare earth pairs.