Optical response from terahertz to visible light of electronuclear transitions in udLiYF4:Ho3+

摘要

Because of its role as a model system with tunable quantum fluctuations and quenched disorder, and the desireudfor optical control and readout of its states, we have used high-resolution optical absorption spectroscopy toudmeasure the crystal-field excitations for Ho3+ ions in LiHoxY1−xF4 from the terahertz to visible regimes. Weudshow that many of the excitations yield very narrow lines visibly split even by the nuclear hyperfine interaction,udmaking Ho3+ in LiHoxY1−xF4 a candidate host for optically addressable electronuclear qubits with quality factorsudas high as Q = 4.7 × 105, where the higher-lying levels are electronic singlets. Optical transitions in the easilyudaccessible near- and mid-infrared are narrow enough to allow readout of the ground-state electronuclear qubitsudresponsible for the interesting magnetism of LiHoxY1−xF4. While many of the higher-lying states have beenudobserved previously, we also report here detailed spectra of terahertz excitations. The strengths of the electricudand magnetic dipole crystal-field transition lines of five of the lowest excited spin-orbit manifolds of diluteudLiYF4:Ho3+ were calculated and compared with measurement. The magnitude of the nuclear hyperfine couplingudwas used to assign the correct upper and lower states to transition lines.