Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2605.07332 · Physical review. B./Physical review. B

Clock-transition-enabled long electron spin coherence of telecom emitters in \texorpdfstring{$\mathbf{CeO}_2$}{CeO2}

Basanta Mistri, Vishal Ranjan, Siddharth Dhomkar

quant-phSubmitted May 8, 2026• Announced May 11, 2026• 0 citations• Revised Oct 11, 2026 (v2)
v1 · May 8, 2026v2 · Oct 11, 2026v3 · Oct 15, 2026
arXivHTMLPDF

Abstract

Rare-earth-ion-doped crystals has emerged as a promising platform for quantum technologies, owing to their narrow telecom-band optical emission, long spin memory, and compatibility with silicon integrated photonic architectures. However, the realization of scalable quantum devices requires host materials with intrinsically dilute spin environments to suppress decoherence. In this context, erbium (Er$^{3+}$) doped cerium oxide (CeO$_2$) is an attractive candidate due to the ultra-low concentration of nuclear spins in the host matrix and its compatibility with silicon-based technologies. Here we perform a comprehensive investigation of the coherence properties of Er$^{3+}$ electron spin qubit in CeO$_2$ via semiclassical as well as detailed cluster correlation expansion simulations. By systematically exploring magnetic field strength, pulse sequences, erbium concentration, and spin temperature, we identify regimes where decoherence from the spin bath is strongly suppressed. Our investigations illustrate that at dilute doping concentration (of the order of 10 ppb) and sub-Kelvin temperatures, operation near clock transitions enables Hahn-echo coherence times to approach the second timescale even at natural isotopic abundance. Importantly, from a practical standpoint, coherence times on the order of $\sim 10$ ms are expected even at liquid helium temperature (about 2 K) for similar concentrations. Moreover, we demonstrate that an additional enhancement can be obtained with conventional multi-$π$-pulse dynamical decoupling protocols. Thus, our findings establish Er$^{3+}$ doped CeO$_2$ as a front-runner for realizing spin qubits, quantum memories, and integrated quantum networks.

Comments
12 pages, 8 figures

Related papers

Optical and spin coherence of Er spin qubits in epitaxial cerium dioxide on silicon

Jiefei Zhang, Gregory D. Grant, Ignas Masiulionis +9 more

Robust spin-photon interfaces with optical transitions in the telecommunication band are essential for quantum networking technologies. Erbium (Er) ions are the ideal candidate with environmentally protected transitions in telecom-C band. Finding the right technologically compatible host material to enable long-lived spins remains a major hurdle. We introduce a new platform based on Er ions in cerium dioxide (CeO 2 ) as a nearly-zero nuclear spin environment (0.04%) epitaxially grown on silicon, offering silicon compatibility for opto-electrical devices. Our studies focus on Er 3+ ions and show a narrow homogeneous linewidth of 440 kHz with an optical coherence time of 0.72 μs at 3.6 K. The reduced nuclear spin noise enables a slow spin-lattice relaxation with a spin relaxation time up to 2.5 ms and an electron spin coherence time of 0.66 μs (in the isolated ion limit) at 3.6 K. These findings highlight the potential of Er 3+ :CeO 2 platform for quantum networks applications.

arXiv:2309.16785•npj Quantum Information•Nov 20, 2024•19 citations

Spin Decoherence Dynamics of Er 3 + in CeO 2 Films

Sagar Kumar Seth, Jonah Nagura, Vrindaa Somjit +10 more

Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er^{3+}) exhibit a unique combination of a telecom (1.5 μm) optical transition and an effective spin-1/2 ground state, but identifying a host that enables heterogeneous device integration while preserving long optical and spin coherence remains an open challenge. We explore the potential of Er^{3+}:CeO_{2} films on silicon and study the Er^{3+} spin coherence, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 μs spin coherence, which can be extended to 176.4 μs with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion induced by bath Er^{3+} spin flip-flops as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.

Physical Review Letters•Nov 24, 2025•8 citations

Spin decoherence dynamics of Er$^{3+}$ in CeO$_2$ film

Sagar Kumar Seth, Jonah Nagura, Vrindaa Somjit +10 more

Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er$^{3+}$) exhibit a unique combination of a telecom (1.5 $μ$m) optical transition and an effective spin-$1/2$ ground state, but identifying a host that enables heterogeneous device integration while preserving long optical and spin coherence remains an open challenge. We explore a new platform of Er$^{3+}$:CeO$_2$ films on silicon, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 $μ$s spin coherence, which can be extended to 176.4\nobreakspace $μ$s with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion-induced Er$^{3+}$ spin flips as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.

arXiv:2508.12429•Aug 17, 2025•0 citations

Optical and microstructural characterization of Er3+ doped epitaxial cerium oxide on silicon

Gregory D. Grant, Jiefei Zhang, Ignas Masiulionis +15 more

Rare-earth ion dopants in solid-state hosts are ideal candidates for quantum communication technologies, such as quantum memories, due to the intrinsic spin–photon interface of the rare-earth ion combined with the integration methods available in the solid state. Erbium-doped cerium oxide (Er:CeO2) is a particularly promising host material platform for such a quantum memory, as it combines the telecom-wavelength (∼1.5μm) 4f–4f transition of erbium, a predicted long electron spin coherence time when embedded in CeO2, and a small lattice mismatch with silicon. In this work, we report on the epitaxial growth of Er:CeO2 thin films on silicon using molecular beam epitaxy, with controlled erbium concentration between 2 and 130 parts per million (ppm). We carry out a detailed microstructural study to verify the CeO2 host structure and characterize the spin and optical properties of the embedded Er3+ ions as a function of doping density. In as-grown Er:CeO2 in the 2–3 ppm regime, we identify an EPR linewidth of 245(1) MHz, an optical inhomogeneous linewidth of 9.5(2) GHz, an optical excited state lifetime of 3.5(1) ms, and a spectral diffusion-limited homogeneous linewidth as narrow as 4.8(3) MHz. We test the annealing of Er:CeO2 films up to 900 °C, which yields narrowing of the inhomogeneous linewidth by 20% and extension of the excited state lifetime by 40%.

arXiv:2309.16644•APL Materials•Feb 1, 2024•25 citations

Isotopically enriched epitaxial CaWO$_{4}$ thin films for Er$^{3+}$ spin-photon quantum interfaces

Hanlin Tang, Kidae Shin, Ashwin K. Boddeti +10 more

Rare earth ion (REI)-doped oxide thin films are attractive for the application of quantum interconnects due to their stable optical levels and scalability$^{1-3}$. Among them, Er$^{3+}$ doped CaWO$_{4}$ is promising because it possesses narrow optical linewidth transitions and a long spin coherence time$^{4-6}$. The electron spin coherence is limited at high temperatures by paramagnetic impurities and by the presence of the 14.3% $^{183}$W nuclear spin. To further increase the spin coherence time at millikelvin temperatures, where the paramagnetic impurities are frozen out, our approach is to synthesize chemically and isotopically purified thin films as a host material. We first grow non-isotopically enriched Er$^{3+}$ doped CaWO$_{4}$ thin films, which exhibit a 214(13) MHz photoluminescence (PL) inhomogeneous linewidth, indicating the thin film has high crystalline quality. We then grow isotopically enriched CaWO$_{4}$ thin films using an isotopically purified $^{186}$WO$_{3}$ source. Time of flight secondary ion mass spectrometry (ToF-SIMS) was used to measure the relative concentration of W isotopes. $^{183}$W, the only W isotope that has a net nuclear spin and is the major cause of spin decoherence, was at a relative abundance of 1.2%, a factor of 10 lower than natural abundance. We also observed PL emission from single ions after integrating nano-photonic devices with the thin film. These results establish isotopically engineered CaWO$_{4}$ thin films as a promising platform for future studies of nuclear-spin-limited coherence and for scalable rare-earth-ion-based quantum nanophotonic devices.

quant-pharXiv:2604.24582•Apr 28, 2026•0 citations

Robust Millisecond Coherence Times of Erbium Electron Spins

Shobhit Gupta, Xuntao Wu, Haitao Zhang +2 more

Erbium-doped solids are prime candidates for quantum memories in optical quantum networks given their telecom-compatible photon emission. An electron spin of erbium with millisecond coherence time is desirable for generating remote entanglement between adjacent quantum network nodes. Here we report GHz-range electron-spin transitions of ${}^{167}{\mathrm{Er}}^{3+}$ in a yttrium oxide (${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$) matrix with coherence times that are consistently longer than a millisecond. By polarizing paramagnetic impurity spins we achieve a spin ${T}_{2}$ up to 1.46 ms, and up to 7.1 ms after dynamical decoupling. These coherence lifetimes are among the longest found for erbium in crystalline matrices despite the presence of host nuclear spins. We further enhance the coherence time beyond conventional dynamical decoupling, using customized sequences to simultaneously mitigate spectral diffusion and dipolar interactions. Our study not only establishes ${}^{167}{\mathrm{Er}}^{3+}$: ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ as a significant quantum memory platform but also provides a guideline for engineering long-lived erbium spins in a variety of host materials for quantum technologies.

arXiv:2207.02708•Physical Review Applied•Apr 10, 2023•29 citations
Clock-transition-enabled long electron spin coherence of telecom emitters in \texorpdfstring{CeO2\mathbf{CeO}_2CeO2​}{CeO2}
Rare-earth-ion-doped crystals has emerged as a promising platform for quantum technologies, owing to their narrow telecom-band optical emission, long spin memory, and compatibility with silicon integrated photonic architectures. However, the realization of scalable quantum devices requires host materials with intrinsically dilute spin environments to suppress decoherence. In this context, erbium (Er3+^{3+}3+) doped cerium oxide (CeO2_22​) is an attractive candidate due to the ultra-low concentration of nuclear spins in the host matrix and its compatibility with silicon-based technologies. Here we perform a comprehensive investigation of the coherence properties of Er3+^{3+}3+ electron spin qubit in CeO2_22​ via semiclassical as well as detailed cluster correlation expansion simulations. By systematically exploring magnetic field strength, pulse sequences, erbium concentration, and spin temperature, we identify regimes where decoherence from the spin bath is strongly suppressed. Our investigations illustrate that at dilute doping concentration (of the order of 10 ppb) and sub-Kelvin temperatures, operation near clock transitions enables Hahn-echo coherence times to approach the second timescale even at natural isotopic abundance. Importantly, from a practical standpoint, coherence times on the order of ∼10\sim 10∼10 ms are expected even at liquid helium temperature (about 2 K) for similar concentrations. Moreover, we demonstrate that an additional enhancement can be obtained with conventional multi-πππ-pulse dynamical decoupling protocols. Thus, our findings establish Er3+^{3+}3+ doped CeO2_22​ as a front-runner for realizing spin qubits, quantum memories, and integrated quantum networks.
Robust spin-photon interfaces with optical transitions in the telecommunication band are essential for quantum networking technologies. Erbium (Er) ions are the ideal candidate with environmentally protected transitions in telecom-C band. Finding the right technologically compatible host material to enable long-lived spins remains a major hurdle. We introduce a new platform based on Er ions in cerium dioxide (CeO 2 ) as a nearly-zero nuclear spin environment (0.04%) epitaxially grown on silicon, offering silicon compatibility for opto-electrical devices. Our studies focus on Er 3+ ions and show a narrow homogeneous linewidth of 440 kHz with an optical coherence time of 0.72 μs at 3.6 K. The reduced nuclear spin noise enables a slow spin-lattice relaxation with a spin relaxation time up to 2.5 ms and an electron spin coherence time of 0.66 μs (in the isolated ion limit) at 3.6 K. These findings highlight the potential of Er 3+ :CeO 2 platform for quantum networks applications.
Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er^{3+}) exhibit a unique combination of a telecom (1.5 μm) optical transition and an effective spin-1/2 ground state, but identifying a host that enables heterogeneous device integration while preserving long optical and spin coherence remains an open challenge. We explore the potential of Er^{3+}:CeO_{2} films on silicon and study the Er^{3+} spin coherence, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 μs spin coherence, which can be extended to 176.4 μs with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion induced by bath Er^{3+} spin flip-flops as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.
Spin decoherence dynamics of Er3+^{3+}3+ in CeO2_22​ film
Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er3+^{3+}3+) exhibit a unique combination of a telecom (1.5 μμμm) optical transition and an effective spin-1/21/21/2 ground state, but identifying a host that enables heterogeneous device integration while preserving long optical and spin coherence remains an open challenge. We explore a new platform of Er3+^{3+}3+:CeO2_22​ films on silicon, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 μμμs spin coherence, which can be extended to 176.4\nobreakspace μμμs with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion-induced Er3+^{3+}3+ spin flips as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.
Rare-earth ion dopants in solid-state hosts are ideal candidates for quantum communication technologies, such as quantum memories, due to the intrinsic spin–photon interface of the rare-earth ion combined with the integration methods available in the solid state. Erbium-doped cerium oxide (Er:CeO2) is a particularly promising host material platform for such a quantum memory, as it combines the telecom-wavelength (∼1.5μm) 4f–4f transition of erbium, a predicted long electron spin coherence time when embedded in CeO2, and a small lattice mismatch with silicon. In this work, we report on the epitaxial growth of Er:CeO2 thin films on silicon using molecular beam epitaxy, with controlled erbium concentration between 2 and 130 parts per million (ppm). We carry out a detailed microstructural study to verify the CeO2 host structure and characterize the spin and optical properties of the embedded Er3+ ions as a function of doping density. In as-grown Er:CeO2 in the 2–3 ppm regime, we identify an EPR linewidth of 245(1) MHz, an optical inhomogeneous linewidth of 9.5(2) GHz, an optical excited state lifetime of 3.5(1) ms, and a spectral diffusion-limited homogeneous linewidth as narrow as 4.8(3) MHz. We test the annealing of Er:CeO2 films up to 900 °C, which yields narrowing of the inhomogeneous linewidth by 20% and extension of the excited state lifetime by 40%.
Isotopically enriched epitaxial CaWO4_{4}4​ thin films for Er3+^{3+}3+ spin-photon quantum interfaces
Rare earth ion (REI)-doped oxide thin films are attractive for the application of quantum interconnects due to their stable optical levels and scalability1−3^{1-3}1−3. Among them, Er3+^{3+}3+ doped CaWO4_{4}4​ is promising because it possesses narrow optical linewidth transitions and a long spin coherence time4−6^{4-6}4−6. The electron spin coherence is limited at high temperatures by paramagnetic impurities and by the presence of the 14.3% 183^{183}183W nuclear spin. To further increase the spin coherence time at millikelvin temperatures, where the paramagnetic impurities are frozen out, our approach is to synthesize chemically and isotopically purified thin films as a host material. We first grow non-isotopically enriched Er3+^{3+}3+ doped CaWO4_{4}4​ thin films, which exhibit a 214(13) MHz photoluminescence (PL) inhomogeneous linewidth, indicating the thin film has high crystalline quality. We then grow isotopically enriched CaWO4_{4}4​ thin films using an isotopically purified 186^{186}186WO3_{3}3​ source. Time of flight secondary ion mass spectrometry (ToF-SIMS) was used to measure the relative concentration of W isotopes. 183^{183}183W, the only W isotope that has a net nuclear spin and is the major cause of spin decoherence, was at a relative abundance of 1.2%, a factor of 10 lower than natural abundance. We also observed PL emission from single ions after integrating nano-photonic devices with the thin film. These results establish isotopically engineered CaWO4_{4}4​ thin films as a promising platform for future studies of nuclear-spin-limited coherence and for scalable rare-earth-ion-based quantum nanophotonic devices.
Erbium-doped solids are prime candidates for quantum memories in optical quantum networks given their telecom-compatible photon emission. An electron spin of erbium with millisecond coherence time is desirable for generating remote entanglement between adjacent quantum network nodes. Here we report GHz-range electron-spin transitions of 167Er3+{}^{167}{\mathrm{Er}}^{3+}167Er3+ in a yttrium oxide (Y2O3{\mathrm{Y}}_{2}{\mathrm{O}}_{3}Y2​O3​) matrix with coherence times that are consistently longer than a millisecond. By polarizing paramagnetic impurity spins we achieve a spin T2{T}_{2}T2​ up to 1.46 ms, and up to 7.1 ms after dynamical decoupling. These coherence lifetimes are among the longest found for erbium in crystalline matrices despite the presence of host nuclear spins. We further enhance the coherence time beyond conventional dynamical decoupling, using customized sequences to simultaneously mitigate spectral diffusion and dipolar interactions. Our study not only establishes 167Er3+{}^{167}{\mathrm{Er}}^{3+}167Er3+: Y2O3{\mathrm{Y}}_{2}{\mathrm{O}}_{3}Y2​O3​ as a significant quantum memory platform but also provides a guideline for engineering long-lived erbium spins in a variety of host materials for quantum technologies.