Spectroscopy of Erbium-167 doped yttrium orthosilicate for quantum photonic technologies*

Rare-earth ions in crystals are one of the most promising candidates for quantum memories due to their long optical and spin coherence times. They have been used to realize solid-state quantum memories in bulk crystals and in nanophotonics devices. Erbium is of particular interest because it has an optical transition in the telecom band, which allows integration with silicon photonics and telecommunication compatibility. Recently, erbium-167 doped yttrium orthosilicate has been shown to have good properties for quantum memories. With a nuclear spin of 7/2, erbium-167 has 16 hyperfine levels in the optical ground state manifold, which can be used as shelving levels for spectral holeburning, and to store coherence in the nuclear spin.

We study erbium-167 doped yttrium orthosilicate at dilution refrigerator temperatures and in a magnetic field. We obtain long hyperfine lifetimes approaching 30 minutes, observe good spectral hole burning and characterize the optical coherence properties. These properties point to a very promising material for optical quantum memories.