Hyperfine structure, optical dephasing, and spectral-hole lifetime of single-crystalline Pr³⁺:La₂(WO₄)₃

Most of the experiments related to quantum information applications, involving rare-earth doped inorganic crystals, are performed on yttrium orthosilicate single crystals. The work presented here is motivated by the search of new compounds which can be used in the field of quantum computing and/or quantum storage. Relaxation times and hyperfine structure of the ³H₄(0)→¹D₂(0) transition in 1.4% Pr³⁺:La₂(WO₄)₃ at 4 K have been measured by photon-echo and spectral-hole-burning techniques. The hyperfine splittings of the ground ³H₄(0) and the excited ¹D₂(0) states are 14.9±0.1 MHz, 24.6±0.1 MHz and 5.0±0.1 MHz, 7.3±0.1 MHz, respectively. An inhomogeneous linewidth of 18.8±0.1 GHz was measured. A homogeneous linewidth of 25.3±2.0 kHz was obtained with or without an external magnetic field of about 14 mT. The fluorescence dynamics of the ¹D₂ level obtained by a direct excitation in the ³H₄→¹D₂ transition gives a nonexponential decay which indicates energy-transfer processes. This decay can be accurately fitted by the Inokuti-Hirayama model [ J. Chem. Phys. 43 1978 (1965)] with a radiative lifetime of 61±1 μs giving a minimal homogeneous linewidth of 2.6 kHz. The spectral-hole lifetime due to population redistribution within the ground hyperfine levels is 16±2 s. The results obtained for the La₂(WO₄)₃ compound make this crystal an interesting host for quantum applications.