Journal article

Optical response from terahertz to visible light of electronuclear transitions in LiYF4:Ho3+

Because of its role as a model system with tunable quantum fluctuations and quenched disorder, and the desire for optical control and readout of its states, we have used high-resolution optical absorption spectroscopy to measure the crystal-field excitations for Ho3+ ions in LiHoxY1-xF4 from the terahertz to visible regimes. We show that many of the excitations yield very narrow lines visibly split even by the nuclear hyperfine interaction, making Ho3+ in LiHoxY1-xF4 a candidate host for optically addressable electronuclear qubits with quality factors as high as Q = 4.7 x 10(5), where the higher-lying levels are electronic singlets. Optical transitions in the easily accessible near-and mid-infrared are narrow enough to allow readout of the ground-state electronuclear qubits responsible for the interesting magnetism of LiHoxY1-xF4. While many of the higher-lying states have been observed previously, we also report here detailed spectra of terahertz excitations. The strengths of the electric and magnetic dipole crystal-field transition lines of five of the lowest excited spin-orbit manifolds of dilute LiYF4:Ho3+ were calculated and compared with measurement. The magnitude of the nuclear hyperfine coupling was used to assign the correct upper and lower states to transition lines.


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