Spectroscopic investigations of Pr3+:CaWO4 at liquid-helium temperatures

Rare-earth ions doped into low nuclear-spin density host crystals provide a promising platform for quantum information storage and processing. Calcium tungstate (CaWO4) is an attractive host crystal because it can be isotopically enriched to provide a nuclear spin free environment. Here, we report a spectroscopic investigation of the optical transitions and hyperfine transitions of praseodymium (141Pr3+) doped in CaWO4 at liquid-helium temperatures. The hyperfine structures of the 3H4(0) and 1D2(0) states are determined by spectral hole burning. The results indicate that Pr3+:CaWO4 is an appealing candidate for quantum memory in quantum information processing.