arXiv:2107.04186 · Physical Review A

High-resolution spectroscopy of neutral Yb atoms in a solid Ne matrix

Ricardo Lewis Lambo, Chenyu Xu, S. T. Pratt, Haiping Xu, Jake Zappala, K. Bailey, Zheng‐Tian Lu, Peter Mueller, Thomas P. O’Connor, Б.Б. Каморзин, Dmitry S. Bezrukov, Y.-Q. Xie, Alexei A. Buchachenko, Jaideep Taggart Singh

Published Dec 16, 2021• 8 citations

arXiv HTML PDF

Abstract

We present an experimental and theoretical study of the absorption and emission spectra of Yb atoms in a solid Ne matrix at a resolution of 0.025 nm. Five absorption bands were identified as due to transitions from the $4{f}^{14}5{d}^{0}6{s}^{2}{\phantom{\rule{4pt}{0ex}}}^{1}{S}_{0}$ ground-state configuration to $4{f}^{14}5{d}^{0}6s6p$ and $4{f}^{13}5{d}^{1}6{s}^{2}$ configurations. The two lowest-energy bands were assigned to outer-shell transitions to $6s6p{\phantom{\rule{4pt}{0ex}}}^{3}{P}_{1}$ and ${}^{1}{P}_{1}$ atomic states and displayed the structure of a broad doublet and an asymmetric triplet, respectively. The remaining three higher-frequency bands were assigned to inner-shell transitions to distinct $J=1$ states arising from the $4{f}^{13}5{d}^{1}6{s}^{2}$ configuration and were highly structured with narrow linewidths. A classical simulation was performed to identify the stability and symmetry of possible trapping sites in the Ne crystal. It showed that the overarching $1+2$ structure of the high-frequency bands could be predominantly ascribed to crystal-field splitting in the axial field of a 10-atom vacancy of ${C}_{4v}$ symmetry. Their prominent substructures were shown to be manifestations of phonon sidebands associated with the zero-phonon lines on each crystal-field state. Unprecedented for a metal--rare-gas system, resolution of individual phonon states on an allowed electronic transition was possible under excitation spectroscopy which reflects the semiquantum nature of solid Ne. In contrast to the absorption spectra, emission spectra produced by steady-state excitation into the ${}^{1}{P}_{1}$ absorption band consisted of simple, unstructured fluorescence bands.

DOI: 10.1103/physreva.104.062809

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Triplet emission of atomic ytterbium isolated in a xenon matrix

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Low Temperature PhysicsJul 1, 20194 citations

High-Resolution Three-Photon Spectroscopy of 6s15pP11,3 Rydberg States of Yb

U. Majewski, Jörg Neukammer, Herbert H. Rinneberg

Physical Review LettersOct 10, 198316 citations

Optical spectroscopy and decoherence studies of Yb3+ :YAG at 968 nm

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Telecom-Band Optical Transitions of Erbium Atoms in Rare-Gas Solids

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quant-pharXiv:2610.00918Oct 2, 20260 citations

Heat- and light-induced transformations of Yb trapping sites in an Ar matrix

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The Journal of Chemical PhysicsNov 6, 201515 citations

Laser spectroscopy of thulium atoms implanted in liquid and solid 4 He

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Physical review. B, Condensed matterJul 1, 199736 citations

arXiv:2107.04186 · Physical Review A

High-resolution spectroscopy of neutral Yb atoms in a solid Ne matrix

Published Dec 16, 2021• 8 citations

arXiv HTML PDF

Abstract

4{f}^{14}5{d}^{0}6{s}^{2}{\phantom{\rule{4pt}{0ex}}}^{1}{S}_{0}

ground-state configuration to

4{f}^{14}5{d}^{0}6s6p

and

4{f}^{13}5{d}^{1}6{s}^{2}

configurations. The two lowest-energy bands were assigned to outer-shell transitions to

6s6p{\phantom{\rule{4pt}{0ex}}}^{3}{P}_{1}

and

{}^{1}{P}_{1}

atomic states and displayed the structure of a broad doublet and an asymmetric triplet, respectively. The remaining three higher-frequency bands were assigned to inner-shell transitions to distinct

J=1

states arising from the

4{f}^{13}5{d}^{1}6{s}^{2}

configuration and were highly structured with narrow linewidths. A classical simulation was performed to identify the stability and symmetry of possible trapping sites in the Ne crystal. It showed that the overarching

1+2

structure of the high-frequency bands could be predominantly ascribed to crystal-field splitting in the axial field of a 10-atom vacancy of

{C}_{4v}

symmetry. Their prominent substructures were shown to be manifestations of phonon sidebands associated with the zero-phonon lines on each crystal-field state. Unprecedented for a metal--rare-gas system, resolution of individual phonon states on an allowed electronic transition was possible under excitation spectroscopy which reflects the semiquantum nature of solid Ne. In contrast to the absorption spectra, emission spectra produced by steady-state excitation into the

{}^{1}{P}_{1}

absorption band consisted of simple, unstructured fluorescence bands.

DOI: 10.1103/physreva.104.062809

Related papers

Triplet emission of atomic ytterbium isolated in a xenon matrix

Nadezhda N. Kleshchina, Inna S. Kalinina, Ricardo Lewis Lambo +3 more

The electronic transitions of ytterbium atoms in a solid Xe matrix grown at 4.8 K are investigated. Absorption bands are detected in the regions of the gas-phase 6s2 1S0 → 4f135d6s2 and 6s2 1S0 → 6s6p 1P1 transitions. Both bands indicate that Yb atoms occupy multiple trapping sites, of which three are identified. Emission induced by the 6s2 1S0 → 6s6p 1P1 excitation is found to be concentrated entirely in the region of the 6s6p 3PJ → 6s2 1S0 decay, whereas the singlet emission is completely quenched. Multiple emission peaks are observed and the effects of annealing and prolonged irradiation on their amplitudes are found to be significant and are interpreted as a consequence of Yb population transfer from one type of site to another. Modeling of the ground-state site structure and stability predicts three Yb/Xe occupation types, substitutional (ss), tetravacancy (tv) and hexavacancy (hv), in order of decreasing stability. Their tentative associations with observed absorption and emission features are discussed. Time correlated single photon spectroscopy is used to determine the lifetimes of the individual emission bands. They are found to be different from each other with indications of a mixture of short- and long- lived 6s6p 3PJ fine-structure components and demonstrate distinct temperature dependencies. A dramatic decrease in the lifetime of the emission peak tentatively assigned to the most stable site with temperature is explained by a competition between the radiative and non-radiative decay paths of the 6s6p 3P1 state. The mechanism of the latter can be attributed to electron–phonon coupling as confirmed by a model of the temperature-dependence of the lifetime.The electronic transitions of ytterbium atoms in a solid Xe matrix grown at 4.8 K are investigated. Absorption bands are detected in the regions of the gas-phase 6s2 1S0 → 4f135d6s2 and 6s2 1S0 → 6s6p 1P1 transitions. Both bands indicate that Yb atoms occupy multiple trapping sites, of which three are identified. Emission induced by the 6s2 1S0 → 6s6p 1P1 excitation is found to be concentrated entirely in the region of the 6s6p 3PJ → 6s2 1S0 decay, whereas the singlet emission is completely quenched. Multiple emission peaks are observed and the effects of annealing and prolonged irradiation on their amplitudes are found to be significant and are interpreted as a consequence of Yb population transfer from one type of site to another. Modeling of the ground-state site structure and stability predicts three Yb/Xe occupation types, substitutional (ss), tetravacancy (tv) and hexavacancy (hv), in order of decreasing stability. Their tentative associations with observed absorption and emission features are discussed. Time correlated single photon spectroscopy is used to determine the lifetimes of the individual emission bands. They are found to be different from each other with indications of a mixture of short- and long- lived 6s6p 3PJ fine-structure components and demonstrate distinct temperature dependencies. A dramatic decrease in the lifetime of the emission peak tentatively assigned to the most stable site with temperature is explained by a competition between the radiative and non-radiative decay paths of the 6s6p 3P1 state. The mechanism of the latter can be attributed to electron–phonon coupling as confirmed by a model of the temperature-dependence of the lifetime.

Low Temperature PhysicsJul 1, 20194 citations

High-Resolution Three-Photon Spectroscopy of 6s15pP11,3 Rydberg States of Yb

U. Majewski, Jörg Neukammer, Herbert H. Rinneberg

High-resolution three-photon laser spectroscopy has been performed for the first time to gain new spectroscopic information. Starting from the $6{s}^{2}^{1}S_{0}$ ground state of Yb, $6s15p^{1,3}P_{1}$ Rydberg states were populated by two-photon-resonant, three-photon absorption via the $6s7s^{1}S_{0}$ intermediate level. As a result of two-photon line narrowing Doppler-free spectra, showing well resolved isotope shifts and hyperfine structures, were obtained. From the hyperfine coupling constants $^{171,173}A(^{1}P_{1})$ the singlet-triplet mixing was derived.High-resolution three-photon laser spectroscopy has been performed for the first time to gain new spectroscopic information. Starting from the $6{s}^{2}^{1}S_{0}$ ground state of Yb, $6s15p^{1,3}P_{1}$ Rydberg states were populated by two-photon-resonant, three-photon absorption via the $6s7s^{1}S_{0}$ intermediate level. As a result of two-photon line narrowing Doppler-free spectra, showing well resolved isotope shifts and hyperfine structures, were obtained. From the hyperfine coupling constants $^{171,173}A(^{1}P_{1})$ the singlet-triplet mixing was derived.

Physical Review LettersOct 10, 198316 citations

Optical spectroscopy and decoherence studies of Yb3+ :YAG at 968 nm

Thomas Böttger, Charles W. Thiel, R. L. Cone +2 more

The $^{2}F_{7/2}\ensuremath{\leftrightarrow}^{2}F_{5/2}$ optical transitions of $\mathrm{Y}{\mathrm{b}}^{3+}$ doped into ${\mathrm{Y}}_{3}\mathrm{A}{\mathrm{l}}_{5}{\mathrm{O}}_{12}$ (YAG) were studied for potential quantum information and photonic signal processing applications. Absorption and fluorescence spectroscopy located the energy levels of the ground $^{2}F_{7/2}$ and excited $^{2}F_{5/2}$ manifolds, allowing inconsistencies between previous assignments of crystal field splittings in the literature to be resolved. These measurements reveal an unusually large splitting between the first and second levels in both the ground and excited multiplets, potentially providing for reduced sensitivity to thermally induced decoherence and spin-lattice relaxation. Spectral hole burning through two-level saturation was observed, determining the excited state lifetime to be 860 \ensuremath{\mu}s and resolving ambiguities in previous fluorescence measurements that were caused by the large radiation trapping effects in this material. Optical decoherence measurements using two-pulse photon echoes gave a homogeneous linewidth of 18 kHz for an applied magnetic field of 1 T, narrowing to 5 kHz at 2.5 T. The observed decoherence was described by spectral diffusion attributed to $\mathrm{Y}{\mathrm{b}}^{3+}\mathrm{\ensuremath{-}}\mathrm{Y}{\mathrm{b}}^{3+}$ magnetic dipole interactions. Laser absorption determined an inhomogeneous linewidth of 3.6 GHz for this transition in this 0.05%-doped crystal, which is narrower than for any other rare-earth-ion transition previously studied in the YAG host. The temperature dependence of the transition energy and linewidth of the lowest $^{2}F_{7/2}$ to lowest $^{2}F_{5/2}$ transition centered at 968.571 nm measured from 4 K to 300 K was well described by phonon scattering at higher temperatures, with an additional anomalous linear temperature-dependent broadening at temperatures below 80 K. Two magnetically inequivalent subgroups of $\mathrm{Y}{\mathrm{b}}^{3+}$ ions were identified when a magnetic field was applied along the $\ensuremath{\langle}111\ensuremath{\rangle}$ axis, as expected for the ${D}_{2}$ sites in the cubic symmetry crystal, with ground and excited state effective $g$ -values of ${g}_{\mathrm{g}}=3.40$ (3.34) and ${g}_{\mathrm{e}}=1.04$ (2.01), respectively. Together with the convenient diode laser wavelength of this transition, our study suggests that $\mathrm{Y}{\mathrm{b}}^{3+}$ :YAG is a promising material system for spectral hole burning and quantum information applications.The $^{2}F_{7/2}\ensuremath{\leftrightarrow}^{2}F_{5/2}$ optical transitions of $\mathrm{Y}{\mathrm{b}}^{3+}$ doped into ${\mathrm{Y}}_{3}\mathrm{A}{\mathrm{l}}_{5}{\mathrm{O}}_{12}$ (YAG) were studied for potential quantum information and photonic signal processing applications. Absorption and fluorescence spectroscopy located the energy levels of the ground $^{2}F_{7/2}$ and excited $^{2}F_{5/2}$ manifolds, allowing inconsistencies between previous assignments of crystal field splittings in the literature to be resolved. These measurements reveal an unusually large splitting between the first and second levels in both the ground and excited multiplets, potentially providing for reduced sensitivity to thermally induced decoherence and spin-lattice relaxation. Spectral hole burning through two-level saturation was observed, determining the excited state lifetime to be 860 \ensuremath{\mu}s and resolving ambiguities in previous fluorescence measurements that were caused by the large radiation trapping effects in this material. Optical decoherence measurements using two-pulse photon echoes gave a homogeneous linewidth of 18 kHz for an applied magnetic field of 1 T, narrowing to 5 kHz at 2.5 T. The observed decoherence was described by spectral diffusion attributed to $\mathrm{Y}{\mathrm{b}}^{3+}\mathrm{\ensuremath{-}}\mathrm{Y}{\mathrm{b}}^{3+}$ magnetic dipole interactions. Laser absorption determined an inhomogeneous linewidth of 3.6 GHz for this transition in this 0.05%-doped crystal, which is narrower than for any other rare-earth-ion transition previously studied in the YAG host. The temperature dependence of the transition energy and linewidth of the lowest $^{2}F_{7/2}$ to lowest $^{2}F_{5/2}$ transition centered at 968.571 nm measured from 4 K to 300 K was well described by phonon scattering at higher temperatures, with an additional anomalous linear temperature-dependent broadening at temperatures below 80 K. Two magnetically inequivalent subgroups of $\mathrm{Y}{\mathrm{b}}^{3+}$ ions were identified when a magnetic field was applied along the $\ensuremath{\langle}111\ensuremath{\rangle}$ axis, as expected for the ${D}_{2}$ sites in the cubic symmetry crystal, with ground and excited state effective $g$-values of ${g}_{\mathrm{g}}=3.40$ (3.34) and ${g}_{\mathrm{e}}=1.04$ (2.01), respectively. Together with the convenient diode laser wavelength of this transition, our study suggests that $\mathrm{Y}{\mathrm{b}}^{3+}$:YAG is a promising material system for spectral hole burning and quantum information applications.

Physical review. B./Physical review. BJul 26, 201628 citations

Telecom-Band Optical Transitions of Erbium Atoms in Rare-Gas Solids

Evgenii Zaitsev, Alec Dinerstein, Shan Zou +6 more

Rare-earth (RE) atoms, such as erbium (Er), have inner-shell optical transitions in the near-infrared, some of which are in the telecom bands. These transitions are largely insensitive to the host environment due to effective shielding by the filled outer shells. Cryogenic rare-gas (RG) solids, such as solid neon (Ne) and argon (Ar), combine high chemical purity with a nearly nuclear-spin-free environment, making them attractive solid hosts for preserving optical and spin coherence. In this work, we isolate neutral Er atoms in solid Ne and Ar at 6 K and characterize their emission by steady-state and time-resolved photoluminescence (PL) spectroscopy. In both hosts, we observe several near-infrared transitions between 1000--1500 nm, including inner-shell emission in the telecom O and E bands. The $4f \rightarrow 5d$ transition near 1299 nm forms a multiplet of narrow components, consistent with crystal-field splitting, and decays on a microsecond timescale. The $4f \rightarrow 4f$ transition near 1437 nm shows a matrix shift below 1 cm $^{-1}$ in both hosts. In solid Ne, its inhomogeneous linewidth is bounded by the spectrometer resolution to < 22 GHz, and its PL lifetime reaches up to 78.9 ms, close to the estimated radiative limit. Thermal annealing extends the 1437 nm lifetime in Ne and suppresses the phonon sidebands relative to the zero-phonon lines in Ar. These results identify RG solids as promising hosts for long-lived telecom-band Er emission and provide a foundation for future spin-photon interfaces and hybrid quantum architectures.Rare-earth (RE) atoms, such as erbium (Er), have inner-shell optical transitions in the near-infrared, some of which are in the telecom bands. These transitions are largely insensitive to the host environment due to effective shielding by the filled outer shells. Cryogenic rare-gas (RG) solids, such as solid neon (Ne) and argon (Ar), combine high chemical purity with a nearly nuclear-spin-free environment, making them attractive solid hosts for preserving optical and spin coherence. In this work, we isolate neutral Er atoms in solid Ne and Ar at 6 K and characterize their emission by steady-state and time-resolved photoluminescence (PL) spectroscopy. In both hosts, we observe several near-infrared transitions between 1000--1500 nm, including inner-shell emission in the telecom O and E bands. The $4f \rightarrow 5d$ transition near 1299 nm forms a multiplet of narrow components, consistent with crystal-field splitting, and decays on a microsecond timescale. The $4f \rightarrow 4f$ transition near 1437 nm shows a matrix shift below 1 cm$^{-1}$ in both hosts. In solid Ne, its inhomogeneous linewidth is bounded by the spectrometer resolution to < 22 GHz, and its PL lifetime reaches up to 78.9 ms, close to the estimated radiative limit. Thermal annealing extends the 1437 nm lifetime in Ne and suppresses the phonon sidebands relative to the zero-phonon lines in Ar. These results identify RG solids as promising hosts for long-lived telecom-band Er emission and provide a foundation for future spin-photon interfaces and hybrid quantum architectures.

quant-pharXiv:2610.00918Oct 2, 20260 citations

Heat- and light-induced transformations of Yb trapping sites in an Ar matrix

Lei-Gang Tao, Nadezhda N. Kleshchina, Ricardo Lewis Lambo +4 more

The low-lying electronic states of Yb isolated in a solid Ar matrix grown at 4.2 K are characterized through absorption and emission spectroscopy. Yb atoms are found to occupy three distinct thermally stable trapping sites labeled "red," "blue," and "violet" according to the relative positions of the absorption features they produce. Classical simulations of the site structure and relative stability broadly reproduced the experimentally observed matrix-induced frequency shifts and thus identified the red, blue, and violet sites as due to respective single substitutional (ss), tetravacancy (Tv), and hexavacancy (Hv) occupation. Prolonged excitation of the (1)S → (1)P transition was found to transfer the Yb population from hv sites into Tv and ss sites. The process showed reversibility in that annealing to 24 K predominantly transferred the Tv population back into Hv sites. Population kinetics were used to deduce the effective rate parameters for the site transformation processes. Experimental observations indicate that the blue and violet sites lie close in energy, whereas the red one is much less stable. Classical simulations identify the blue site as the most stable one.The low-lying electronic states of Yb isolated in a solid Ar matrix grown at 4.2 K are characterized through absorption and emission spectroscopy. Yb atoms are found to occupy three distinct thermally stable trapping sites labeled "red," "blue," and "violet" according to the relative positions of the absorption features they produce. Classical simulations of the site structure and relative stability broadly reproduced the experimentally observed matrix-induced frequency shifts and thus identified the red, blue, and violet sites as due to respective single substitutional (ss), tetravacancy (Tv), and hexavacancy (Hv) occupation. Prolonged excitation of the (1)S → (1)P transition was found to transfer the Yb population from hv sites into Tv and ss sites. The process showed reversibility in that annealing to 24 K predominantly transferred the Tv population back into Hv sites. Population kinetics were used to deduce the effective rate parameters for the site transformation processes. Experimental observations indicate that the blue and violet sites lie close in energy, whereas the red one is much less stable. Classical simulations identify the blue site as the most stable one.

The Journal of Chemical PhysicsNov 6, 201515 citations

Laser spectroscopy of thulium atoms implanted in liquid and solid 4 He

Kiyoshi Ishikawa, A. Hatakeyama, Koichi Gosyono-o +3 more

The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state ${4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}$ , which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10 ${}^{10}$ --10 ${}^{11}$ atoms/cm ${}^{3}$ . The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the ${4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}$ ${(6,5/2)}_{7/2}$ state of free thulium atoms. The excited state is expected to be a mixed state of the ${4f}^{12}{5d6s}^{2}$ and ${4f}^{13}6s6p$ configurations. The metastable state ${4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}$ is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state ${4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}$, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10${}^{10}$--10${}^{11}$ atoms/cm${}^{3}$. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the ${4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}$ ${(6,5/2)}_{7/2}$ state of free thulium atoms. The excited state is expected to be a mixed state of the ${4f}^{12}{5d6s}^{2}$ and ${4f}^{13}6s6p$ configurations. The metastable state ${4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}$ is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.

Physical review. B, Condensed matterJul 1, 199736 citations

4{f}^{14}5{d}^{0}6{s}^{2}{\phantom{\rule{4pt}{0ex}}}^{1}{S}_{0}

ground-state configuration to

4{f}^{14}5{d}^{0}6s6p

and

4{f}^{13}5{d}^{1}6{s}^{2}

configurations. The two lowest-energy bands were assigned to outer-shell transitions to

6s6p{\phantom{\rule{4pt}{0ex}}}^{3}{P}_{1}

and

{}^{1}{P}_{1}

atomic states and displayed the structure of a broad doublet and an asymmetric triplet, respectively. The remaining three higher-frequency bands were assigned to inner-shell transitions to distinct

J=1

states arising from the

4{f}^{13}5{d}^{1}6{s}^{2}

1+2

structure of the high-frequency bands could be predominantly ascribed to crystal-field splitting in the axial field of a 10-atom vacancy of

{C}_{4v}

{}^{1}{P}_{1}

absorption band consisted of simple, unstructured fluorescence bands.

High-resolution three-photon laser spectroscopy has been performed for the first time to gain new spectroscopic information. Starting from the $6{s}^{2}^{1}S_{0}$ ground state of Yb,

6s15p^{1,3}P_{1}

Rydberg states were populated by two-photon-resonant, three-photon absorption via the

6s7s^{1}S_{0}

intermediate level. As a result of two-photon line narrowing Doppler-free spectra, showing well resolved isotope shifts and hyperfine structures, were obtained. From the hyperfine coupling constants

^{171,173}A(^{1}P_{1})

the singlet-triplet mixing was derived.

The $^{2}F_{7/2}\ensuremath{\leftrightarrow}^{2}F_{5/2}$ optical transitions of

\mathrm{Y}{\mathrm{b}}^{3+}

doped into

{\mathrm{Y}}_{3}\mathrm{A}{\mathrm{l}}_{5}{\mathrm{O}}_{12}

(YAG) were studied for potential quantum information and photonic signal processing applications. Absorption and fluorescence spectroscopy located the energy levels of the ground

^{2}F_{7/2}

and excited

^{2}F_{5/2}

manifolds, allowing inconsistencies between previous assignments of crystal field splittings in the literature to be resolved. These measurements reveal an unusually large splitting between the first and second levels in both the ground and excited multiplets, potentially providing for reduced sensitivity to thermally induced decoherence and spin-lattice relaxation. Spectral hole burning through two-level saturation was observed, determining the excited state lifetime to be 860 \ensuremath{\mu}s and resolving ambiguities in previous fluorescence measurements that were caused by the large radiation trapping effects in this material. Optical decoherence measurements using two-pulse photon echoes gave a homogeneous linewidth of 18 kHz for an applied magnetic field of 1 T, narrowing to 5 kHz at 2.5 T. The observed decoherence was described by spectral diffusion attributed to $\mathrm{Y}{\mathrm{b}}^{3+}\mathrm{\ensuremath{-}}\mathrm{Y}{\mathrm{b}}^{3+}$ magnetic dipole interactions. Laser absorption determined an inhomogeneous linewidth of 3.6 GHz for this transition in this 0.05%-doped crystal, which is narrower than for any other rare-earth-ion transition previously studied in the YAG host. The temperature dependence of the transition energy and linewidth of the lowest

^{2}F_{7/2}

to lowest

^{2}F_{5/2}

transition centered at 968.571 nm measured from 4 K to 300 K was well described by phonon scattering at higher temperatures, with an additional anomalous linear temperature-dependent broadening at temperatures below 80 K. Two magnetically inequivalent subgroups of

\mathrm{Y}{\mathrm{b}}^{3+}

ions were identified when a magnetic field was applied along the $\ensuremath{\langle}111\ensuremath{\rangle}$ axis, as expected for the

{D}_{2}

sites in the cubic symmetry crystal, with ground and excited state effective

g

-values of

{g}_{\mathrm{g}}=3.40

(3.34) and

{g}_{\mathrm{e}}=1.04

(2.01), respectively. Together with the convenient diode laser wavelength of this transition, our study suggests that

\mathrm{Y}{\mathrm{b}}^{3+}

:YAG is a promising material system for spectral hole burning and quantum information applications.

4f \rightarrow 5d

transition near 1299 nm forms a multiplet of narrow components, consistent with crystal-field splitting, and decays on a microsecond timescale. The

4f \rightarrow 4f

transition near 1437 nm shows a matrix shift below 1 cm

^{-1}

in both hosts. In solid Ne, its inhomogeneous linewidth is bounded by the spectrometer resolution to < 22 GHz, and its PL lifetime reaches up to 78.9 ms, close to the estimated radiative limit. Thermal annealing extends the 1437 nm lifetime in Ne and suppresses the phonon sidebands relative to the zero-phonon lines in Ar. These results identify RG solids as promising hosts for long-lived telecom-band Er emission and provide a foundation for future spin-photon interfaces and hybrid quantum architectures.

{4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}

, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10

{}^{10}

--10

{}^{11}

atoms/cm

{}^{3}

. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the

{4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}

{(6,5/2)}_{7/2}

state of free thulium atoms. The excited state is expected to be a mixed state of the

{4f}^{12}{5d6s}^{2}

and

{4f}^{13}6s6p

configurations. The metastable state

{4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}

is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.