Optical Coherent Transients and Hole Burning of the Elemental FLUORINE-7 - Elemental DEUTERIUM-5 Transition in Europium-Hydroxide

Michael S. Otteson, R. L. Cone, R. M. Macfarlane +1 more

Michael S. Otteson

Mikhail Solonenko

T. Muramoto, Shunsuke Nakanishi, T. Hashi

F. Chiossi, Diana Serrano, Alexey Tiranov +1 more

We report the optical study of europium nitrate hexahydrate crystals Eu(NO 3 ) ⋅ 3 6H 2 O and their deuterated version Eu(NO 3 ) ⋅ 3 6D 2 O conducted at 50 mK. The crystals show sub-GHz inhomogeneous linewidths for the F 0 7 ↔ 5 D 0 transition and optical coherence times up to 136 μs for the non-deuterated crystal and 750 μs for the deuterated one. In addition, using the spectral hole burning technique, the hyperfine splittings in the absence of an external field have been estimated for the ground and optical levels. These results suggest that rare-earth nitrate crystals could represent a promising class of materials for quantum information applications as well as for fundamental physics experiments requiring narrow optical transitions and good coherence properties. • Deuterated and non-deuterated europium nitrate crystals were grown using the slow-cooling method. • Optical coherence times up to 0.75 ms were measured at 50 mK using the photon echo technique. • Sub-GHz optical inhomogeneous linewidths were observed. • The hyperfine splittings of the ground and optical states were assessed via spectral hole burning.

Thomas Schmidt, R. M. Macfarlane, Silvia Volker

Persistent and time-resolved transient holes were burnt into the $^{1}\mathrm{D}_{2}$${\ensuremath{\leftarrow}}^{3}$${\mathrm{H}}_{4}$ transition of ${\mathrm{Pr}}^{3+}$ and the $^{5}\mathrm{D}_{0}$${\ensuremath{\leftarrow}}^{7}$${\mathrm{F}}_{0}$ transition of ${\mathrm{Eu}}^{3+}$ in silicate glasses. The holewidths were studied as a function of burning-fluence density, wavelength, and temperature between 0.4 and 12 K. Transient holes arising from optical pumping of ground-state nuclear hyperfine levels were found for both ions at T3 K. Their lifetime decreases with increasing temperature. They are accompanied by symmetrically placed antiholes. For ${\mathrm{Eu}}^{3+}$, two pairs of antiholes were found which are attributed to the two europium isotopes, $^{151}\mathrm{Eu}$ and $^{153}\mathrm{Eu}$. For ${\mathrm{Pr}}^{3+}$, an additional mechanism leading to persistent hole burning dominates above 3 K. The holewidth follows a ${\mathit{T}}^{(1.3\ifmmode\pm\else\textpm\fi{}0.1)}$ dependence for ${\mathrm{Pr}}^{3+}$ and a ${\mathit{T}}^{(1.0\ifmmode\pm\else\textpm\fi{}0.1)}$ dependence for ${\mathrm{Eu}}^{3+}$. The temperature dependence is the same as that of the contribution of the two-level systems to the specific heat measured on the same samples and in the same temperature range. The quadrupole splittings of the $^{7}\mathrm{F}_{0}$ ground state and the crystal-field splittings of the $^{7}\mathrm{F}_{1}$ and $^{7}\mathrm{F}_{2}$ levels of ${\mathrm{Eu}}^{3+}$ as a function of excitation wavelength indicate that the strength of the noncubic component of the crystal field varies monotonically for excitation across the $^{5}\mathrm{D}_{0}$${\ensuremath{\leftarrow}}^{7}$${\mathrm{F}}_{0}$ absorption band, falling to zero at the long-wavelength edge. The hole width shows a similar variation with excitation frequency. No influence of the experimental time scale on the hole width was detected for either sample between ${10}^{\mathrm{\ensuremath{-}}2}$ and ${10}^{2}$ s.