Physical review. B, Condensed matter

Temperature and concentration dependence of optical dephasing, spectral-hole lifetime, and anisotropic absorption in Eu 3 + : Y 2 SiO 5

Flurin Könz, Y. Sun, Charles W. Thiel, R. L. Cone, Randy W. Equall, Ralph L. Hutcheson, R. M. Macfarlane

Published Aug 25, 2003• 195 citations

Abstract

Detailed site-selective spectroscopy has been performed as a function of temperature on the ${}^{7}{F}_{0}{\ensuremath{\leftrightarrow}}^{5}{D}_{0}$ transition of ${\mathrm{Eu}}^{3+}:{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ for ${\mathrm{Eu}}^{3+}$ concentrations of 0.02%, 0.1%, 0.5%, and 1%. Time-domain optical dephasing, spectral hole lifetimes, anisotropic absorption coefficients, inhomogeneous linewidths, and fluorescence lifetimes for ${\mathrm{Eu}}^{3+}$ ions at both crystallographic sites were measured. The temperature dependence of the optical dephasing, transition energy, and linewidth of the ${}^{7}{\stackrel{\ensuremath{\rightarrow}}{{F}_{0}}}^{5}{D}_{0}$ absorption was measured and interpreted in terms of Raman scattering of phonons. Photon echo measurements of optical dephasing gave ${T}_{2}$ values as long as 2.6 ms, approaching the limit set by the fluorescence decay time. Spectral hole lifetimes were measured for temperatures from 2 K to 18 K, with observed lifetimes varying from 1 s at 18 K to an estimated value of greater than 20 days at 2 K. Anisotropic absorption coefficients were measured, and an increase in ${\mathrm{Eu}}^{3+}$ concentration from 0.02% to 7% produced an increase in the inhomogeneous linewidth ${\ensuremath{\Gamma}}_{\mathrm{inh}}$ from 0.5 GHz to \ensuremath{\sim}150 GHz, indicating that ${\mathrm{Eu}}^{3+}$ doping induces significant strain in the crystal. New determinations of many energy levels of ${}^{7}{F}_{J}$ multiplets have been made for $J=0$ to 6.

DOI: 10.1103/physrevb.68.085109

Related papers

Optical dephasing, hyperfine structure, and hyperfine relaxation associated with the 580.8-nm F07 −5 D0 transition of europium in Eu3+ : Y2 O3

William Randall Babbitt, A. Lezama, THOMAS W. MOSSBERG

Physical review. B, Condensed matterFeb 1, 198970 citations

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

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

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

Anisotropic Optical-Response of Eu-doped Yttrium Orthosilicate

Huimin Liu, M. L. Santiago, Weiyi Jia +1 more

NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and EducationFeb 22, 19980 citations

Spectroscopy and coherence lifetime extension of hyperfine transitions in 151 Eu 3 + :Y 2 SiO 5

Andrea Arcangeli, Marko Lovrić, Biagio Tumino +2 more

Physical Review BMay 28, 201440 citations

^7F_0-^5D_1 Transition in Eu^3+:Y_2SiO_5

Xiao A. Shen, Ravinder Kachru

Journal of the Optical Society of America BApr 1, 199413 citations

Optical decoherence, spectroscopy, and magnetic g tensors for the 1.5-µm I 15 / 2 4 − I 13 / 2 4 transitions of E r 3 + dopants at the C 2 -symmetry site in Y 2 O 3

Thomas Böttger, Todd L. Harris, G. D. Reinemer +2 more

Physical review. B./Physical review. BJul 17, 20248 citations

Physical review. B, Condensed matter

Temperature and concentration dependence of optical dephasing, spectral-hole lifetime, and anisotropic absorption in Eu 3 + : Y 2 SiO 5

Flurin Könz, Y. Sun, Charles W. Thiel, R. L. Cone, Randy W. Equall, Ralph L. Hutcheson, R. M. Macfarlane

Published Aug 25, 2003• 195 citations

Publisher

Abstract

Detailed site-selective spectroscopy has been performed as a function of temperature on the

{}^{7}{F}_{0}{\ensuremath{\leftrightarrow}}^{5}{D}_{0}

transition of

{\mathrm{Eu}}^{3+}:{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}

for

{\mathrm{Eu}}^{3+}

concentrations of 0.02%, 0.1%, 0.5%, and 1%. Time-domain optical dephasing, spectral hole lifetimes, anisotropic absorption coefficients, inhomogeneous linewidths, and fluorescence lifetimes for

{\mathrm{Eu}}^{3+}

ions at both crystallographic sites were measured. The temperature dependence of the optical dephasing, transition energy, and linewidth of the

{}^{7}{\stackrel{\ensuremath{\rightarrow}}{{F}_{0}}}^{5}{D}_{0}

absorption was measured and interpreted in terms of Raman scattering of phonons. Photon echo measurements of optical dephasing gave

{T}_{2}

values as long as 2.6 ms, approaching the limit set by the fluorescence decay time. Spectral hole lifetimes were measured for temperatures from 2 K to 18 K, with observed lifetimes varying from 1 s at 18 K to an estimated value of greater than 20 days at 2 K. Anisotropic absorption coefficients were measured, and an increase in

{\mathrm{Eu}}^{3+}

concentration from 0.02% to 7% produced an increase in the inhomogeneous linewidth

{\ensuremath{\Gamma}}_{\mathrm{inh}}

from 0.5 GHz to \ensuremath{\sim}150 GHz, indicating that

{\mathrm{Eu}}^{3+}

doping induces significant strain in the crystal. New determinations of many energy levels of

{}^{7}{F}_{J}

multiplets have been made for

J=0

to 6.

DOI: 10.1103/physrevb.68.085109

Related papers

Optical dephasing, hyperfine structure, and hyperfine relaxation associated with the 580.8-nm F07 −5 D0 transition of europium in Eu3+ : Y2 O3

William Randall Babbitt, A. Lezama, THOMAS W. MOSSBERG

We have employed spectral-hole-burning, coherent-transient, and optical-rf double-resonance techniques to measure various parameters associated with the 580.8-nm $^{7}\mathrm{F}_{0}$ ${\mathrm{\ensuremath{-}}}^{5}$ ${\mathrm{D}}_{0}$ transition of ${\mathrm{Eu}}^{3+}$ doped into ${\mathrm{Y}}_{2}$ ${\mathrm{O}}_{3}$ . In particular, we have measured the hyperfine splittings of the terminal levels (for both $^{151}\mathrm{Eu}$ and $^{153}\mathrm{Eu}$ ), an effective thermalization rate of the ground-state ${(}^{7}$ ${\mathrm{F}}_{0}$ ) hyperfine manifold over the temperature range of \ensuremath{\simeq}4--15 K, and the homogeneous linewidth of the optical transition over the range of \ensuremath{\simeq}14--35 K. Large ratios of inhomogeneous to homogeneous linewidth at elevated temperatures ( ${10}^{3}$ at 25 K) and long ground-state hyperfine thermalization times (>30 h at 4 K) make this an interesting crystal in the context of spectrally addressable optical memories.We have employed spectral-hole-burning, coherent-transient, and optical-rf double-resonance techniques to measure various parameters associated with the 580.8-nm $^{7}\mathrm{F}_{0}$${\mathrm{\ensuremath{-}}}^{5}$${\mathrm{D}}_{0}$ transition of ${\mathrm{Eu}}^{3+}$ doped into ${\mathrm{Y}}_{2}$${\mathrm{O}}_{3}$. In particular, we have measured the hyperfine splittings of the terminal levels (for both $^{151}\mathrm{Eu}$ and $^{153}\mathrm{Eu}$), an effective thermalization rate of the ground-state ${(}^{7}$${\mathrm{F}}_{0}$) hyperfine manifold over the temperature range of \ensuremath{\simeq}4--15 K, and the homogeneous linewidth of the optical transition over the range of \ensuremath{\simeq}14--35 K. Large ratios of inhomogeneous to homogeneous linewidth at elevated temperatures (${10}^{3}$ at 25 K) and long ground-state hyperfine thermalization times (>30 h at 4 K) make this an interesting crystal in the context of spectrally addressable optical memories.

Physical review. B, Condensed matterFeb 1, 198970 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

Anisotropic Optical-Response of Eu-doped Yttrium Orthosilicate

Huimin Liu, M. L. Santiago, Weiyi Jia +1 more

Eu-doped yttrium orthosilicate (Eu(3+) : Y2SiO5) had been a subject being investigated for coherent time-domain optical memory and information processing applications since its ultraslow optical dephasing was discovered several years ago. In this crystal the weakly allowed (7)F0 - (5)D0 transition of europium ions exhibits a sufficient long dephasing time and no spectral difli.usion on a time scale of several hours at low temperature, thus an information pattern or data can be stored as a population grating in the ground state hyperfine levels. On the other hand, the study on photon-echo relaxation shows that the dephasing time T2 of Eu (3+) and other rare-earth ions doped YAG, YAlO3 strongly depends on the intensity of the excitation pulses. In Eu (3+) :YAlO3, an exponential decay of photon-echo with T2 = 53 microseconds if the excitation pulses are weak (5 vJ/pulse) was observed. However, when the excitation pulses are strong (80 pJ/pulse) they observed a much shortened T2 with a highly nonexponential decay pattern. The conclusion they derived is that the intensity-dependent dephasing rate effects are quite general, and it depends on how much the excitation intensity varies. In this paper we use transient grating formation technique showing that a temporal lattice distortion may only occur along crystal c axis, caused by EU (3+) excitation. At high excitation level the produced exciton in conduction band may also couple to the dynamical lattice relaxation process, giving rise to an apparently much shortened dephasing time.Eu-doped yttrium orthosilicate (Eu(3+) : Y2SiO5) had been a subject being investigated for coherent time-domain optical memory and information processing applications since its ultraslow optical dephasing was discovered several years ago. In this crystal the weakly allowed (7)F0 - (5)D0 transition of europium ions exhibits a sufficient long dephasing time and no spectral difli.usion on a time scale of several hours at low temperature, thus an information pattern or data can be stored as a population grating in the ground state hyperfine levels. On the other hand, the study on photon-echo relaxation shows that the dephasing time T2 of Eu (3+) and other rare-earth ions doped YAG, YAlO3 strongly depends on the intensity of the excitation pulses. In Eu (3+) :YAlO3, an exponential decay of photon-echo with T2 = 53 microseconds if the excitation pulses are weak (5 vJ/pulse) was observed. However, when the excitation pulses are strong (80 pJ/pulse) they observed a much shortened T2 with a highly nonexponential decay pattern. The conclusion they derived is that the intensity-dependent dephasing rate effects are quite general, and it depends on how much the excitation intensity varies. In this paper we use transient grating formation technique showing that a temporal lattice distortion may only occur along crystal c axis, caused by EU (3+) excitation. At high excitation level the produced exciton in conduction band may also couple to the dynamical lattice relaxation process, giving rise to an apparently much shortened dephasing time.

NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and EducationFeb 22, 19980 citations

Spectroscopy and coherence lifetime extension of hyperfine transitions in 151 Eu 3 + :Y 2 SiO 5

Andrea Arcangeli, Marko Lovrić, Biagio Tumino +2 more

We report a low-temperature spectroscopic characterization of the ground-state hyperfine transitions in ${}^{151}\mathrm{Eu}{}^{3+}{\mathrm{:Y}}_{2}{\mathrm{SiO}}_{5}$ via coherent Raman scattering. Inhomogeneous linewidths of 21 and 38 kHz were measured for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ and the $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{5}{2}$ ground-state transitions, respectively. Spin-echo decays were recorded for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ transition at zero field and for a small static magnetic field. In the latter case, analysis by a simple model gave an amplitude of 284 Hz and a correlation time of 3.5 ms for the transition frequency fluctuations. Application of a dynamical decoupling sequence resulted in coherence lifetimes up to 474 ms, an 18-fold increase compared to the spin intrinsic phase memory time of 26 ms.We report a low-temperature spectroscopic characterization of the ground-state hyperfine transitions in ${}^{151}\mathrm{Eu}{}^{3+}{\mathrm{:Y}}_{2}{\mathrm{SiO}}_{5}$ via coherent Raman scattering. Inhomogeneous linewidths of 21 and 38 kHz were measured for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ and the $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{5}{2}$ ground-state transitions, respectively. Spin-echo decays were recorded for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ transition at zero field and for a small static magnetic field. In the latter case, analysis by a simple model gave an amplitude of 284 Hz and a correlation time of 3.5 ms for the transition frequency fluctuations. Application of a dynamical decoupling sequence resulted in coherence lifetimes up to 474 ms, an 18-fold increase compared to the spin intrinsic phase memory time of 26 ms.

Physical Review BMay 28, 201440 citations

^7F_0-^5D_1 Transition in Eu^3+:Y_2SiO_5

Xiao A. Shen, Ravinder Kachru

We report a spectroscopic study of the 7F0–5D1 transition of europium ions in crystal yttrium orthosilicate (Eu3+:Y2SiO5) with a focus on low-temperature properties relevant to its use in time-domain optical data storage. The optical dephasing time T2 for this green transition was found to be approximately 50 μs for Eu3+ in one optical site (site 1) and 56 μs for Eu3+ in the other site (site 2), both of which exceeded their respective excited-state lifetimes (32 μs for site 1 and 42 μs for site 2). Of the two optical sites, the transition on site 2 has a slightly larger inhomogeneous linewidth (~2.7 GHz) but a significantly larger oscillator strength (~6 × 10−8), making it a good candidate for time-domain optical storage. The hyperfine structures of the transition for both sites were also measured by spectral hole burning.We report a spectroscopic study of the 7F0–5D1 transition of europium ions in crystal yttrium orthosilicate (Eu3+:Y2SiO5) with a focus on low-temperature properties relevant to its use in time-domain optical data storage. The optical dephasing time T2 for this green transition was found to be approximately 50 μs for Eu3+ in one optical site (site 1) and 56 μs for Eu3+ in the other site (site 2), both of which exceeded their respective excited-state lifetimes (32 μs for site 1 and 42 μs for site 2). Of the two optical sites, the transition on site 2 has a slightly larger inhomogeneous linewidth (~2.7 GHz) but a significantly larger oscillator strength (~6 × 10−8), making it a good candidate for time-domain optical storage. The hyperfine structures of the transition for both sites were also measured by spectral hole burning.

Journal of the Optical Society of America BApr 1, 199413 citations

Optical decoherence, spectroscopy, and magnetic g tensors for the 1.5-µm I 15 / 2 4 − I 13 / 2 4 transitions of E r 3 + dopants at the C 2 -symmetry site in Y 2 O 3

Thomas Böttger, Todd L. Harris, G. D. Reinemer +2 more

Erbium-doped solids are a promising platform for quantum technology due to the $\mathrm{E}{\mathrm{r}}^{3+}$ 1.5-\textmu{}m optical transition in the telecom C band that can offer long coherence times. To characterize the intrinsic ${\mathrm{C}}_{2}$ site of $\mathrm{E}{\mathrm{r}}^{3+}$ in ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ for quantum information and photonic signal-processing applications, absorption and site-selective fluorescence spectroscopy were used to assign the $\mathrm{E}{\mathrm{r}}^{3+}\phantom{\rule{4pt}{0ex}}^{4}I_{15/2}$ $\ensuremath{\leftrightarrow}$ $^{4}I_{13/2}$ transitions. The lowest-to-lowest transition occurs at 1535.608 nm and laser absorption determined an inhomogeneous linewidth of 780 MHz in a 0.005%-doped crystal at 3.4 K. Time-resolved fluorescence established an upper limit for the excited-state lifetime of 8.5 ms. Angular-dependent Zeeman absorption was used to determine ground- and excited-state $g$ tensors. The ${\mathrm{C}}_{2}$ -site $g$ tensor components for the ground state are ${g}_{x}=1.60$ , ${g}_{y}=4.71$ , and ${g}_{z}=11.93$ with a tipping angle of \ensuremath{\alpha} = $2.{06}^{\ensuremath{\circ}}$, whereas for the excited state the components are ${g}_{x}=1.08$ , ${g}_{y}=4.36$ , and ${g}_{z}=10.07$ with a tipping angle of \ensuremath{\alpha} = $\ensuremath{-}11.{7}^{\ensuremath{\circ}}$. Optical decoherence can be suppressed by the application of a magnetic field parallel to $\ensuremath{\langle}111\ensuremath{\rangle}$ crystal axes where all ${\mathrm{C}}_{2}$ sites become nearly magnetically equivalent with large $g$ values so that spin flips of neighboring $\mathrm{E}{\mathrm{r}}^{3+}$ ions can be simultaneously suppressed. Using this magnetic field direction, two-pulse photon echoes gave a homogeneous linewidth of 5 kHz for an applied magnetic field of 0.5 T, narrowing and saturating at 2.5 kHz at 3.5 T. Decoherence over intermediate magnetic fields was described by spectral diffusion due to $\mathrm{E}{\mathrm{r}}^{3+}\text{\ensuremath{-}}\mathrm{E}{\mathrm{r}}^{3+}$ magnetic dipole interactions driven by the direct phonon process. With $\mathrm{E}{\mathrm{r}}^{3+}$ : ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ absorption at a convenient telecom laser wavelength and the ability to fabricate waveguides, our study suggests that this is a promising material system for quantum information and spectral hole-burning signal-processing applications.Erbium-doped solids are a promising platform for quantum technology due to the $\mathrm{E}{\mathrm{r}}^{3+}$ 1.5-\textmu{}m optical transition in the telecom C band that can offer long coherence times. To characterize the intrinsic ${\mathrm{C}}_{2}$ site of $\mathrm{E}{\mathrm{r}}^{3+}$ in ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ for quantum information and photonic signal-processing applications, absorption and site-selective fluorescence spectroscopy were used to assign the $\mathrm{E}{\mathrm{r}}^{3+}\phantom{\rule{4pt}{0ex}}^{4}I_{15/2}$$\ensuremath{\leftrightarrow}$$^{4}I_{13/2}$ transitions. The lowest-to-lowest transition occurs at 1535.608 nm and laser absorption determined an inhomogeneous linewidth of 780 MHz in a 0.005%-doped crystal at 3.4 K. Time-resolved fluorescence established an upper limit for the excited-state lifetime of 8.5 ms. Angular-dependent Zeeman absorption was used to determine ground- and excited-state $g$ tensors. The ${\mathrm{C}}_{2}$-site $g$ tensor components for the ground state are ${g}_{x}=1.60$, ${g}_{y}=4.71$, and ${g}_{z}=11.93$ with a tipping angle of \ensuremath{\alpha} = $2.{06}^{\ensuremath{\circ}}$, whereas for the excited state the components are ${g}_{x}=1.08$, ${g}_{y}=4.36$, and ${g}_{z}=10.07$ with a tipping angle of \ensuremath{\alpha} = $\ensuremath{-}11.{7}^{\ensuremath{\circ}}$. Optical decoherence can be suppressed by the application of a magnetic field parallel to $\ensuremath{\langle}111\ensuremath{\rangle}$ crystal axes where all ${\mathrm{C}}_{2}$ sites become nearly magnetically equivalent with large $g$ values so that spin flips of neighboring $\mathrm{E}{\mathrm{r}}^{3+}$ ions can be simultaneously suppressed. Using this magnetic field direction, two-pulse photon echoes gave a homogeneous linewidth of 5 kHz for an applied magnetic field of 0.5 T, narrowing and saturating at 2.5 kHz at 3.5 T. Decoherence over intermediate magnetic fields was described by spectral diffusion due to $\mathrm{E}{\mathrm{r}}^{3+}\text{\ensuremath{-}}\mathrm{E}{\mathrm{r}}^{3+}$ magnetic dipole interactions driven by the direct phonon process. With $\mathrm{E}{\mathrm{r}}^{3+}$:${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ absorption at a convenient telecom laser wavelength and the ability to fabricate waveguides, our study suggests that this is a promising material system for quantum information and spectral hole-burning signal-processing applications.

Physical review. B./Physical review. BJul 17, 20248 citations

Detailed site-selective spectroscopy has been performed as a function of temperature on the

{}^{7}{F}_{0}{\ensuremath{\leftrightarrow}}^{5}{D}_{0}

transition of

{\mathrm{Eu}}^{3+}:{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}

for

{\mathrm{Eu}}^{3+}

concentrations of 0.02%, 0.1%, 0.5%, and 1%. Time-domain optical dephasing, spectral hole lifetimes, anisotropic absorption coefficients, inhomogeneous linewidths, and fluorescence lifetimes for

{\mathrm{Eu}}^{3+}

ions at both crystallographic sites were measured. The temperature dependence of the optical dephasing, transition energy, and linewidth of the

{}^{7}{\stackrel{\ensuremath{\rightarrow}}{{F}_{0}}}^{5}{D}_{0}

absorption was measured and interpreted in terms of Raman scattering of phonons. Photon echo measurements of optical dephasing gave

{T}_{2}

{\mathrm{Eu}}^{3+}

concentration from 0.02% to 7% produced an increase in the inhomogeneous linewidth

{\ensuremath{\Gamma}}_{\mathrm{inh}}

from 0.5 GHz to \ensuremath{\sim}150 GHz, indicating that

{\mathrm{Eu}}^{3+}

doping induces significant strain in the crystal. New determinations of many energy levels of

{}^{7}{F}_{J}

multiplets have been made for

J=0

to 6.

We have employed spectral-hole-burning, coherent-transient, and optical-rf double-resonance techniques to measure various parameters associated with the 580.8-nm

^{7}\mathrm{F}_{0}

${\mathrm{\ensuremath{-}}}^{5}$

{\mathrm{D}}_{0}

transition of

{\mathrm{Eu}}^{3+}

doped into

{\mathrm{Y}}_{2}

{\mathrm{O}}_{3}

. In particular, we have measured the hyperfine splittings of the terminal levels (for both

^{151}\mathrm{Eu}

and

^{153}\mathrm{Eu}

), an effective thermalization rate of the ground-state

{(}^{7}

{\mathrm{F}}_{0}

) hyperfine manifold over the temperature range of \ensuremath{\simeq}4--15 K, and the homogeneous linewidth of the optical transition over the range of \ensuremath{\simeq}14--35 K. Large ratios of inhomogeneous to homogeneous linewidth at elevated temperatures (

{10}^{3}

at 25 K) and long ground-state hyperfine thermalization times (>30 h at 4 K) make this an interesting crystal in the context of spectrally addressable optical memories.

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.

We report a low-temperature spectroscopic characterization of the ground-state hyperfine transitions in

{}^{151}\mathrm{Eu}{}^{3+}{\mathrm{:Y}}_{2}{\mathrm{SiO}}_{5}

via coherent Raman scattering. Inhomogeneous linewidths of 21 and 38 kHz were measured for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ and the $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{5}{2}$ ground-state transitions, respectively. Spin-echo decays were recorded for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ transition at zero field and for a small static magnetic field. In the latter case, analysis by a simple model gave an amplitude of 284 Hz and a correlation time of 3.5 ms for the transition frequency fluctuations. Application of a dynamical decoupling sequence resulted in coherence lifetimes up to 474 ms, an 18-fold increase compared to the spin intrinsic phase memory time of 26 ms.

Erbium-doped solids are a promising platform for quantum technology due to the

\mathrm{E}{\mathrm{r}}^{3+}

1.5-\textmu{}m optical transition in the telecom C band that can offer long coherence times. To characterize the intrinsic

{\mathrm{C}}_{2}

site of

\mathrm{E}{\mathrm{r}}^{3+}

{\mathrm{Y}}_{2}{\mathrm{O}}_{3}

for quantum information and photonic signal-processing applications, absorption and site-selective fluorescence spectroscopy were used to assign the

\mathrm{E}{\mathrm{r}}^{3+}\phantom{\rule{4pt}{0ex}}^{4}I_{15/2}

$\ensuremath{\leftrightarrow}$

^{4}I_{13/2}

transitions. The lowest-to-lowest transition occurs at 1535.608 nm and laser absorption determined an inhomogeneous linewidth of 780 MHz in a 0.005%-doped crystal at 3.4 K. Time-resolved fluorescence established an upper limit for the excited-state lifetime of 8.5 ms. Angular-dependent Zeeman absorption was used to determine ground- and excited-state

g

tensors. The

{\mathrm{C}}_{2}

-site

g

tensor components for the ground state are

{g}_{x}=1.60

{g}_{y}=4.71

, and

{g}_{z}=11.93

with a tipping angle of \ensuremath{\alpha} = $2.{06}^{\ensuremath{\circ}}$, whereas for the excited state the components are

{g}_{x}=1.08

{g}_{y}=4.36

, and

{g}_{z}=10.07

with a tipping angle of \ensuremath{\alpha} = $\ensuremath{-}11.{7}^{\ensuremath{\circ}}$. Optical decoherence can be suppressed by the application of a magnetic field parallel to $\ensuremath{\langle}111\ensuremath{\rangle}$ crystal axes where all

{\mathrm{C}}_{2}

sites become nearly magnetically equivalent with large

g

values so that spin flips of neighboring

\mathrm{E}{\mathrm{r}}^{3+}

ions can be simultaneously suppressed. Using this magnetic field direction, two-pulse photon echoes gave a homogeneous linewidth of 5 kHz for an applied magnetic field of 0.5 T, narrowing and saturating at 2.5 kHz at 3.5 T. Decoherence over intermediate magnetic fields was described by spectral diffusion due to $\mathrm{E}{\mathrm{r}}^{3+}\text{\ensuremath{-}}\mathrm{E}{\mathrm{r}}^{3+}$ magnetic dipole interactions driven by the direct phonon process. With

\mathrm{E}{\mathrm{r}}^{3+}

{\mathrm{Y}}_{2}{\mathrm{O}}_{3}

absorption at a convenient telecom laser wavelength and the ability to fabricate waveguides, our study suggests that this is a promising material system for quantum information and spectral hole-burning signal-processing applications.