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Quantum 2.0 Conference and Exhibition

Advancements in Erbium-Doped Silica Fibers for Quantum Networks: Ultra-Long Population Storage and Ultra-Narrow Homogeneous Linewidths at Millikelvin Temperatures

Mahdi Bornadel, Farhad Rasekh, Nasser Gohari Kamel, Sara Shafiei Alavijeh, Erhan Sağlamyürek, Faezeh Kimiaee Asadi, Sourabh Kumar, Daniel Oblak, Christoph Simon

Published Jan 1, 2025• 0 citations
Publisher

Abstract

We demonstrate ultra-long population storage (∼ 9 hours) and ultra-narrow homogeneous linewidths (∼ 8 kHz) in erbium-doped silica fibers (EDF) at ∼ 7 mK using spectral hole burning and photon-echo techniques. These results establish EDF as a strong candidate for fiber-based quantum networks.
DOI
10.1364/quantum.2025.qm4a.6

Related papers

Spin Lifetime Mechanisms in Erbium-Doped Fiber for Quantum Network Applications

Bornadel, Mahdi

Erbium-doped silica fiber (EDF) is evaluated as a telecom-band quantum-memory platform via spectral hole burning at millikelvin temperatures. We map spin-population decay versus temperature (about 7 to 2400 mK) and magnetic field (0 to 200 mT), revealing two relaxation components above about 80 mK and, at about 7 mK, a third, ultra-slow component enabling more than 9 h population storage under optimized field. The relative component weights are nearly condition-independent, consistent with distinct ion classes. A single phenomenological model, combining Er-Er flip-flops, a TLS-mediated direct process with field and temperature scaling, and a Raman-like term, fits all data using shared exponents while allowing mechanism weights to vary between classes. We also observe a Lorentzian-to-Gaussian hole-shape crossover below about 80 mK, pointing to changing broadening mechanisms. These results establish long-lived spin-population storage in standard EDF and delineate a practical operating window. They motivate denser measurements across the below-80 mK crossover, isotope-resolved tests, and complementary optical-coherence studies.

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Ultra-narrow homogeneous linewidths of erbium-doped silica glass fibers at millikelvin temperatures: magnetic field and temperature dependence

Farhad Rasekh, Nasser Gohari Kamel, Mahdi Bornadel +4 more

Erbium-doped solids are promising candidates for fiber-based quantum networks due to their emission wavelength, which aligns with the telecom band over which optical fibers exhibit minimal loss. Among these, erbium-doped silica fiber (EDF) stands out for its availability, ease of use, and seamless integration with existing fiber-optic infrastructure. In this work, using the two-pulse photon-echo (2PPE) technique, we measured the homogeneous linewidth of the 4 I 13/2 ↔ 4 I 15/2 optical transition under varying magnetic fields and temperatures. We observed an effective homogeneous linewidth of approximately 8 kHz at ∼7mK at an optimal magnetic field of 0.09 T, representing over two orders of magnitude improvement compared to earlier reports measured at T ≈700mK. We also present a comprehensive model for the combined magnetic field and temperature dependency of the effective homogeneous linewidth. Additionally, we employed three-pulse photon-echo (3PPE) measurements to investigate spectral diffusion and decoherence processes and conclude that Two-Level System (TLS) effects are significantly suppressed at sufficiently low temperatures, below ∼100mK.

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We use spectral hole burning to investigate spin dynamics within the electronic Zeeman sublevels of the ground state of the erbium ions in erbium-doped fibers (EDF). Conducted at ultra-low temperatures and under varying magnetic fields, our study reveals distinct changes in spin relaxation dynamics across different conditions. We identified three decay components at approximately 7 mK, with one achieving spin lifetimes of over 9 hours under optimal conditions, while two components were observed at higher temperatures. The fairly stable relative weights of the decay components across conditions suggest distinct ion populations contributing to the observed relaxation dynamics. While earlier studies struggled to account for all decay components at higher temperatures, our approach successfully models spin dynamics across all observed decay components, using a consistent set of underlying mechanisms, including spin flip-flop interactions, direct coupling to two-level systems, and Raman-type processes, and distinguishes the decay components by the strengths with which these mechanisms contribute. These results suggest EDFs' potential as a promising candidate for quantum memory applications, with further room for optimization.

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Lucile Veissier, Mohsen Falamarzi Askarani, Thomas Lutz +4 more

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Spectral hole burning in erbium-doped fibers for slow light

Sonia Melle, Óscar G. Calderón, M. A. Antón +2 more

The homogeneous linewidth of the transition I15/24−I13/24 in highly doped erbium fibers and its dependence with temperature in the range from 10 to 50 K are experimentally characterized using spectral hole burning. The homogeneous linewidth dependence with temperature is quadratic above 20 K where homogeneous broadening is dominated by two-phonon Raman processes, and linear at lower temperatures where direct phonon processes occur. This characteristic power-law dependence was also derived from transmittance measurements. The solution of nonlinear field equations using the results obtained from our experiments predicts that Gaussian probe pulses propagate at subluminal speed through the narrow spectral holes burned in erbium-doped fibers. For gigahertz pulses in the telecommunication window, a fractional delay as high as 0.6 is predicted.

Journal of the Optical Society of America B•Jul 30, 2012•6 citations

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Erhan Sağlamyürek, Thomas Lutz, Lucile Veissier +4 more

Long-lived population storage in optically pumped levels of rare-earth ions doped into solids, referred to as persistent spectral hole burning, is of significant fundamental and technological interest. However, the demonstration of deep and persistent holes in rare-earth ion doped amorphous hosts, e.g., glasses, has remained an open challenge for many decades---a fact that motivates our work towards a better understanding of the interaction between impurities and vibrational modes in glasses. Here we report the observation and detailed characterization of such holes in an erbium-doped silica glass fiber cooled to below 1 K. We demonstrate population storage in electronic Zeeman sublevels of the erbium ground state with lifetimes up to 30 seconds and 80% spin polarization. In addition to its fundamental aspect, our investigation reveals a potential technological application of rare-earth ion doped amorphous materials, including at telecommunication wavelength.

arXiv:1507.03012•Physical Review B•Dec 14, 2015•32 citations
Erbium-doped silica fiber (EDF) is evaluated as a telecom-band quantum-memory platform via spectral hole burning at millikelvin temperatures. We map spin-population decay versus temperature (about 7 to 2400 mK) and magnetic field (0 to 200 mT), revealing two relaxation components above about 80 mK and, at about 7 mK, a third, ultra-slow component enabling more than 9 h population storage under optimized field. The relative component weights are nearly condition-independent, consistent with distinct ion classes. A single phenomenological model, combining Er-Er flip-flops, a TLS-mediated direct process with field and temperature scaling, and a Raman-like term, fits all data using shared exponents while allowing mechanism weights to vary between classes. We also observe a Lorentzian-to-Gaussian hole-shape crossover below about 80 mK, pointing to changing broadening mechanisms. These results establish long-lived spin-population storage in standard EDF and delineate a practical operating window. They motivate denser measurements across the below-80 mK crossover, isotope-resolved tests, and complementary optical-coherence studies.
Erbium-doped solids are promising candidates for fiber-based quantum networks due to their emission wavelength, which aligns with the telecom band over which optical fibers exhibit minimal loss. Among these, erbium-doped silica fiber (EDF) stands out for its availability, ease of use, and seamless integration with existing fiber-optic infrastructure. In this work, using the two-pulse photon-echo (2PPE) technique, we measured the homogeneous linewidth of the 4 I 13/2 ↔ 4 I 15/2 optical transition under varying magnetic fields and temperatures. We observed an effective homogeneous linewidth of approximately 8 kHz at ∼7mK at an optimal magnetic field of 0.09 T, representing over two orders of magnitude improvement compared to earlier reports measured at T ≈700mK. We also present a comprehensive model for the combined magnetic field and temperature dependency of the effective homogeneous linewidth. Additionally, we employed three-pulse photon-echo (3PPE) measurements to investigate spectral diffusion and decoherence processes and conclude that Two-Level System (TLS) effects are significantly suppressed at sufficiently low temperatures, below ∼100mK.
We use spectral hole burning to investigate spin dynamics within the electronic Zeeman sublevels of the ground state of the erbium ions in erbium-doped fibers (EDF). Conducted at ultra-low temperatures and under varying magnetic fields, our study reveals distinct changes in spin relaxation dynamics across different conditions. We identified three decay components at approximately 7 mK, with one achieving spin lifetimes of over 9 hours under optimal conditions, while two components were observed at higher temperatures. The fairly stable relative weights of the decay components across conditions suggest distinct ion populations contributing to the observed relaxation dynamics. While earlier studies struggled to account for all decay components at higher temperatures, our approach successfully models spin dynamics across all observed decay components, using a consistent set of underlying mechanisms, including spin flip-flop interactions, direct coupling to two-level systems, and Raman-type processes, and distinguishes the decay components by the strengths with which these mechanisms contribute. These results suggest EDFs' potential as a promising candidate for quantum memory applications, with further room for optimization.
Understanding decoherence in cryogenically cooled rare-earth-ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications. Here we study the coherence properties in a weakly doped erbium silica glass fiber motivated by our recent observation of efficient and long-lived Zeeman sublevel storage in this material and by its potential for applications at telecommunication wavelengths. We analyze photon echo decays as well as the potential mechanisms of spectral diffusion that can be caused by coupling with dynamic disorder modes that are characteristic for glassy hosts, and by the magnetic dipole-dipole interactions between Er3+{\mathrm{Er}}^{3+}Er3+ ions. We also investigate the effective linewidth as a function of magnetic field, temperature, and time, and then present a model that describes these experimental observations. We highlight that the operating conditions (0.6 K and 0.05 T) at which we previously observed efficient spectral hole burning coincide with those for narrow linewidths (1 MHz)---an important property for applications that has not been reported before for a rare-earth-ion doped glass.
The homogeneous linewidth of the transition I15/24−I13/24 in highly doped erbium fibers and its dependence with temperature in the range from 10 to 50 K are experimentally characterized using spectral hole burning. The homogeneous linewidth dependence with temperature is quadratic above 20 K where homogeneous broadening is dominated by two-phonon Raman processes, and linear at lower temperatures where direct phonon processes occur. This characteristic power-law dependence was also derived from transmittance measurements. The solution of nonlinear field equations using the results obtained from our experiments predicts that Gaussian probe pulses propagate at subluminal speed through the narrow spectral holes burned in erbium-doped fibers. For gigahertz pulses in the telecommunication window, a fractional delay as high as 0.6 is predicted.
Long-lived population storage in optically pumped levels of rare-earth ions doped into solids, referred to as persistent spectral hole burning, is of significant fundamental and technological interest. However, the demonstration of deep and persistent holes in rare-earth ion doped amorphous hosts, e.g., glasses, has remained an open challenge for many decades---a fact that motivates our work towards a better understanding of the interaction between impurities and vibrational modes in glasses. Here we report the observation and detailed characterization of such holes in an erbium-doped silica glass fiber cooled to below 1 K. We demonstrate population storage in electronic Zeeman sublevels of the erbium ground state with lifetimes up to 30 seconds and 80% spin polarization. In addition to its fundamental aspect, our investigation reveals a potential technological application of rare-earth ion doped amorphous materials, including at telecommunication wavelength.