Enhancing erbium optical emission rate via careful host crystal selection

Erbium ion (Er³⁺) doped solid-state crystals are a quality candidate for quantum communication technologies. [1-3] However, across common host materials, Er³⁺ is a “dim” ion, with low optical radiative rates in its 1.5 µm transition – of kHz at most except by cavity enhancement. [2-4] This low rate provides insufficient bandwidth for usable quantum information transfer protocols. [5]

One route to higher Er³⁺ radiative emission rates is by careful selection of crystal hosts. The crystal field around an Er³⁺ ion admixes into the 4f¹¹ states a small degree of opposite-parity character, yielding a host-dependent emission rate increase. [6] Via high-throughput computational methods, we estimate the emission rates of Er³⁺ in ~58,000 materials. As verification, the emission rates of ten Er-implanted hosts are measured and compared to the model. Our study shows that some hosts could provide a 10x or more increase in Er³⁺ emission rate compared to common hosts like TiO₂ or CeO₂, providing future avenues towards MHz-bandwidth Er-based quantum memory.

[1] Jiefei Zhang, et al., npj Quantum Information 10(1):119, 2024.

[2] Gregory D. Grant, et al., APL Materials, 12(2), 2024.

[3] Cheng Ji, et al., ACS Nano 18(14):9929-9941, 2024.

[4] Charles W. Thiel, et al., Journal of Luminescence., 131(3): 353-361, 2011.

[5] David D. Awschalom, et al., Technical Report, Argonne National Lab, 2022.

[6] Brian R. Judd, Physical Review, 127(3):750, 1962.