The role of the dopant on electronic structure of Er-doped oxides for quantum memory

Rare earth ion defects in solid-state hosts are excellent candidates for applications in quantum communication technologies as qubit systems, due to their inherent spin-photon interface and long coherence times. ^[1] Er³⁺ is an especially promising candidate due to its ⁴I_15/2 → ⁴I_13/2 transition in the telecom C-band. This classically-forbidden telecom transition is made accessible by placing Er³⁺ ions within a crystal host, which makes the transition sufficiently bright to use for quantum communication. Oxides are an excellent class of hosts for rare-earth ions due to their straightforward growth even at high purity and expected overall good coherence times when hosting defects. ^[2] Here, we show that linewidths in photoluminescence excitation spectra vary with dopant concentration and growth conditions. However, the causes for this variation are unclear. X-ray absorption spectroscopy (XAS) is an element-specific technique broadly applied for local electronic structure characterization in materials. In this work, we performed XAS at the Advanced Photon Source to probe the electronic structure of Er-doped oxides as a function of the doping level. This information is crucial for controlling the tunability of excited state lifetimes and rare-earth defect linewidths in such systems.

References



[1] Zhong, M. et al. Nature, 2015, 517, 177–180.

[2] Kanai S. et al., arXiv, 2021, 2102.02986.