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:2006.09831

Molecule-based coherent light-spin interfaces for quantum information processing -- optical spin state polarization in a binuclear Europium complex

Senthil Kumar Kuppusamy, Diana Serrano, Aline M. Nonat, Benoı̂t Heinrich, Lydia Karmazin‐Brelot, Loı̈c J. Charbonnière, Philippe Goldner, Mario Ruben

Published Jun 17, 2020• 0 citations
arXivHTMLPDF

Abstract

The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ions (REIs) are suitable candidates for QIP protocols due to their extraordinary photo-physical and magnetic quantum properties such as long optical and spin coherence lifetimes ($T_2$). However, molecules incorporating REIs, despite having advantageous properties such as atomically exact quantum tunability, inherent scalability, and large portability, have not yet been studied for QIP applications. As a first testimony of the usefulness of REI molecules for optical QIP applications, we demonstrate in this study that narrow spectral holes can be burned in the inhomogeneously broadened $^5$D$_0\to^7$F$_0$ optical transition of a binuclear Eu(III) complex, rendering a homogeneous linewidth ($Γ_h$) = 22 $\pm$ 1 MHz, which translates as $T_2 = 14.5$ $\pm$ 0.7 ns at 1.4 K. Moreover, long-lived spectral holes are observed, demonstrating efficient polarization of Eu(III) ground state nuclear spins, a fundamental requirement for all-optical spin initialization and addressing. These results elucidate the usefulness of REI-based molecular complexes as versatile coherent light-spin interfaces for applications in quantum communications and processing.

DOI
10.48550/arxiv.2006.09831

Related papers

Optical spin-state polarization in a binuclear europium complex towards molecule-based coherent light-spin interfaces

Senthil Kumar Kuppusamy, Diana Serrano, Aline M. Nonat +5 more

Abstract The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ion (REI)- based molecular systems, whose quantum properties could be tuned taking advantage of molecular engineering strategies, are one of the systems actively pursued for the implementation of QIP schemes. Herein, we demonstrate the efficient polarization of 2 ground-state nuclear spins—a fundamental requirement for all-optical spin initialization and addressing—in a binuclear Eu(III) complex, featuring inhomogeneously broadened 5D0→7 F0 optical transition. At 1.4 K, long-lived spectral holes have been burnt in the transition: homogeneous linewidth (Γh) = 22 +/- 1 MHz, which translates as optical coherence lifetime (T2opt) = 14.5 +/- 0.7 ns, and ground-state spin population lifetime (T1spin) = 1.6 +/- 0.4 s have been obtained. The results presented in this study are a progressive step towards the realization of molecule-based coherent light-spin QIP interfaces.

Nature Communications•Apr 12, 2021•35 citations

Observation of Narrow Optical Homogeneous Linewidth and Long Nuclear Spin Lifetimes in a Prototypical [Eu(trensal)] Complex

Senthil Kumar Kuppusamy, Evgenij Vasilenko, Weizhe Li +5 more

Coherent light–matter interfaces are key elements for many quantum information processing architectures. Rare-earth ion (REI)-containing systems featuring narrow inter-configurational f–f transitions are suitable for creating such interfaces. Recently, narrow homogeneous linewidths (Γ h ) and long nuclear spin lifetimes ( T 1spin ) associated with two Eu 3+ complexes featuring the 5 D 0 → 7 F 0 f–f transition have been reported, elucidating that REI-molecule-based coherent light–matter interfaces can be obtained. In this study, we report a homogeneous linewidth of 2.8 MHz at 4.2 K, corresponding to an optical coherence lifetime ( T 2opt ) of 114 ns (0.11 μs), associated with the 5 D 0 → 7 F 0 transition of the prototypical charge neutral Eu 3+ complex─[Eu(trensal)]. Moreover, we have observed long nuclear spin lifetimes ( T 1spin ) up to 460 ± 80 s at 4.2 K for the complex and efficient optical pumping of hyperfine levels of the 5 D 0 ground state. The results presented in this study indicate that narrow homogeneous linewidths and long nuclear spin lifetimes could be a generic property of molecular Eu 3+ complexes featuring the 5 D 0 → 7 F 0 transition.

The Journal of Physical Chemistry C•May 23, 2023•11 citations

Spectral Hole‐Burning Studies of a Mononuclear Eu(III) Complex Reveal Narrow Optical Linewidths of the 5D0→7F0 Transition and Seconds Long Nuclear Spin Lifetimes

Sören Schlittenhardt, Evgenij Vasilenko, Vishnu Unni Chorakkunnath +5 more

Abstract Coordination complexes of rare‐earth ions (REI) show optical transitions with narrow linewidths enabling the creation of coherent light‐matter interfaces for quantum information processing (QIP) applications. Among the REI‐based complexes, Eu(III) complexes showing the 5D0→7F0 transition are of interest for QIP applications due to the narrow linewidths associated with the transition. Herein, we report on the synthesis, structure, and optical properties of a novel Eu(III) complex and its Gd(III) analogue composed of 2,9‐bis(pyrazol‐1‐yl)‐1,10‐phenanthroline (dpphen) and three nitrate (NO3) ligands. The Eu(III) complex—[Eu(dpphen)(NO3)3]—showed sensitized metal‐centred emission (5D0→7FJ; J=0,1,2,3, 4, 5, or 6) in the visible region, upon irradiation of the ligand‐centred band at 369 nm, with the 5D0→7F0 transition centred at 580.9 nm. Spectral hole‐burning (SHB) studies of the complex with stoichiometric Eu(III) concentration revealed a narrow homogeneous linewidth (Γh) of 1.55 MHz corresponding to a 0.205 μs long optical coherence lifetime (T2opt). Remarkably, long nuclear spin lifetimes (T1spin) of up to 41 s have been observed for the complex. The narrow optical linewidths and long T1spin lifetimes obtained for the Eu(III) complex showcase the utility of Eu(III) complexes as tuneable, following molecular engineering principles, coherent light‐matter interfaces for QIP applications.

ChemPhysChem•Jun 18, 2024•9 citations

Ultralong-lived Coherent States in Eu$^{3+}$:Y$_2$O$_3$ Optical Ceramics for Quantum Memories

Shuping Liu, Ren, Miaomiao, Wanting Xiao +8 more

Rare earth ions (REI) in solid materials are among the leading systems for quantum technology applications. However, developing practical REI quantum devices with long-lived coherent states remains challenging due to great growth difficulties of high-quality REI materials and a lack of comprehensive understanding of REI's decoherence mechanisms. Here we realize a record optical coherence time of 421.5 $\pm$ 10.5 $μ$s for the $^7$F$_0\rightarrow^5$D$_0$ transition and more than 30 hours lifetime for the $^7$F$_0$ hyperfine spin states in Eu$^{3+}$:Y$_2$O$_3$ optical ceramics. We report the elimination of two-level-system induced optical decoherence in short-range ordered crystals. Meanwhile, a new decoherence mechanism caused by new kinds of perturbing magnetic centers is identified below 1.5 K. We further demonstrate the coherent light storage over 5 $μ$s by using the atomic frequency comb protocol. These results open up prospects for the realization of practical quantum memories and large scale quantum communications with REI optical ceramics.

arXiv:2502.16222•Feb 22, 2025•0 citations

Long-lived optical coherence and spin lifetimes in Eu3+:Y2O3 oxide ceramics for quantum memories

Shuping Liu, Miaomiao Ren, Wanting Xiao +8 more

Rare earth ions (REI) in solid materials are among the leading systems for quantum technology applications. However, developing practical REI quantum devices with long-lived coherent states remains challenging due to great difficulties in growing high-quality REI materials and incomplete understanding of their decoherence mechanisms. In this work, we report a long optical coherence time of 422 ± 11 μs for the 7F0 → 5D0 transition, as well as a lifetime exceeding 30 hours for the 7F0 hyperfine spin states in Eu3+:Y2O3 optical ceramics. We identify the absence of two-level-system induced optical decoherence in short-range-ordered crystals and a decoherence mechanism caused by perturbing magnetic centers that were not detected previously below 1.5 K. Furthermore, we demonstrate coherent light storage over 5 μs by using the atomic frequency comb protocol. These results provide a promising proof-of-principle demonstration of quantum memory using Eu3+:Y2O3 optical ceramic system, highlighting its significant potential for practical quantum applications. Rare earth ions (REI) in solids are promising for quantum technologies. Here, the authors demonstrate a record optical coherence lifetime and the absence of two-level-system induced decoherence in Eu3+:Y2O3 optical ceramics. These findings advance the optimization of REI-based quantum systems and enable tailored material designs.

Communications Physics•Aug 18, 2025•6 citations

Controlled ion-ion interactions and cavity-enhanced emission of a coherent dinuclear Eu$^{3+}$ complex

Evgenij Vasilenko, Vishnu Unni Chorakkunnath, Barbora Brachnakova +4 more

Molecular rare-earth-ion complexes offer unique opportunities for quantum technologies by combining the intrinsic coherence properties of rare-earth ions with chemically tunable molecular environments. A crucial capability is the realization of multi-qubit architectures with defined qubit couplings to enable two-qubit quantum gates. Here, we investigate the optical coherence properties and excitation-induced interactions of two Eu$^{3+}$-based molecular complexes, comparing a mononuclear reference system with a dinuclear analogue in which two Eu$^{3+}$ ions are positioned at a well-defined intramolecular distance of about 7 Angstrom. Using cryogenic ensemble spectroscopy, including spectral hole burning, free-induction decay, and photon echo measurements at temperatures down to 100 mK, we demonstrate long optical coherence times $T_{2,\text{o}}$ of up to 9 $μ$s. As a key step toward scalable multi-qubit architectures, a control-target sequence was implemented to probe conditional ion-ion interactions, revealing a stronger interaction-induced dephasing in the dinuclear complex. Finally, we show the integration of the dinuclear complex into a fiber-based optical microcavity, and observe an 380-fold emission enhancement of the $\mathrm{}^5\mathrm{D}_0\rightarrow\mathrm{}^7\mathrm{F}_0$ transition. Together, these results position molecular rare-earth complexes as versatile and chemically tunable building blocks for scalable quantum technologies.

quant-pharXiv:2606.11947•Jun 11, 2026•0 citations
The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ions (REIs) are suitable candidates for QIP protocols due to their extraordinary photo-physical and magnetic quantum properties such as long optical and spin coherence lifetimes (T2T_2T2​). However, molecules incorporating REIs, despite having advantageous properties such as atomically exact quantum tunability, inherent scalability, and large portability, have not yet been studied for QIP applications. As a first testimony of the usefulness of REI molecules for optical QIP applications, we demonstrate in this study that narrow spectral holes can be burned in the inhomogeneously broadened 5^55D0→7_0\to^70​→7F0_00​ optical transition of a binuclear Eu(III) complex, rendering a homogeneous linewidth (ΓhΓ_hΓh​) = 22 ±\pm± 1 MHz, which translates as T2=14.5T_2 = 14.5T2​=14.5 ±\pm± 0.7 ns at 1.4 K. Moreover, long-lived spectral holes are observed, demonstrating efficient polarization of Eu(III) ground state nuclear spins, a fundamental requirement for all-optical spin initialization and addressing. These results elucidate the usefulness of REI-based molecular complexes as versatile coherent light-spin interfaces for applications in quantum communications and processing.
Abstract The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ion (REI)- based molecular systems, whose quantum properties could be tuned taking advantage of molecular engineering strategies, are one of the systems actively pursued for the implementation of QIP schemes. Herein, we demonstrate the efficient polarization of 2 ground-state nuclear spins—a fundamental requirement for all-optical spin initialization and addressing—in a binuclear Eu(III) complex, featuring inhomogeneously broadened 5D0→7 F0 optical transition. At 1.4 K, long-lived spectral holes have been burnt in the transition: homogeneous linewidth (Γh) = 22 +/- 1 MHz, which translates as optical coherence lifetime (T2opt) = 14.5 +/- 0.7 ns, and ground-state spin population lifetime (T1spin) = 1.6 +/- 0.4 s have been obtained. The results presented in this study are a progressive step towards the realization of molecule-based coherent light-spin QIP interfaces.
Coherent light–matter interfaces are key elements for many quantum information processing architectures. Rare-earth ion (REI)-containing systems featuring narrow inter-configurational f–f transitions are suitable for creating such interfaces. Recently, narrow homogeneous linewidths (Γ h ) and long nuclear spin lifetimes ( T 1spin ) associated with two Eu 3+ complexes featuring the 5 D 0 → 7 F 0 f–f transition have been reported, elucidating that REI-molecule-based coherent light–matter interfaces can be obtained. In this study, we report a homogeneous linewidth of 2.8 MHz at 4.2 K, corresponding to an optical coherence lifetime ( T 2opt ) of 114 ns (0.11 μs), associated with the 5 D 0 → 7 F 0 transition of the prototypical charge neutral Eu 3+ complex─[Eu(trensal)]. Moreover, we have observed long nuclear spin lifetimes ( T 1spin ) up to 460 ± 80 s at 4.2 K for the complex and efficient optical pumping of hyperfine levels of the 5 D 0 ground state. The results presented in this study indicate that narrow homogeneous linewidths and long nuclear spin lifetimes could be a generic property of molecular Eu 3+ complexes featuring the 5 D 0 → 7 F 0 transition.
Abstract Coordination complexes of rare‐earth ions (REI) show optical transitions with narrow linewidths enabling the creation of coherent light‐matter interfaces for quantum information processing (QIP) applications. Among the REI‐based complexes, Eu(III) complexes showing the 5D0→7F0 transition are of interest for QIP applications due to the narrow linewidths associated with the transition. Herein, we report on the synthesis, structure, and optical properties of a novel Eu(III) complex and its Gd(III) analogue composed of 2,9‐bis(pyrazol‐1‐yl)‐1,10‐phenanthroline (dpphen) and three nitrate (NO3) ligands. The Eu(III) complex—[Eu(dpphen)(NO3)3]—showed sensitized metal‐centred emission (5D0→7FJ; J=0,1,2,3, 4, 5, or 6) in the visible region, upon irradiation of the ligand‐centred band at 369 nm, with the 5D0→7F0 transition centred at 580.9 nm. Spectral hole‐burning (SHB) studies of the complex with stoichiometric Eu(III) concentration revealed a narrow homogeneous linewidth (Γh) of 1.55 MHz corresponding to a 0.205 μs long optical coherence lifetime (T2opt). Remarkably, long nuclear spin lifetimes (T1spin) of up to 41 s have been observed for the complex. The narrow optical linewidths and long T1spin lifetimes obtained for the Eu(III) complex showcase the utility of Eu(III) complexes as tuneable, following molecular engineering principles, coherent light‐matter interfaces for QIP applications.
Ultralong-lived Coherent States in Eu3+^{3+}3+:Y2_22​O3_33​ Optical Ceramics for Quantum Memories
Rare earth ions (REI) in solid materials are among the leading systems for quantum technology applications. However, developing practical REI quantum devices with long-lived coherent states remains challenging due to great growth difficulties of high-quality REI materials and a lack of comprehensive understanding of REI's decoherence mechanisms. Here we realize a record optical coherence time of 421.5 ±\pm± 10.5 μμμs for the 7^77F0→5_0\rightarrow^50​→5D0_00​ transition and more than 30 hours lifetime for the 7^77F0_00​ hyperfine spin states in Eu3+^{3+}3+:Y2_22​O3_33​ optical ceramics. We report the elimination of two-level-system induced optical decoherence in short-range ordered crystals. Meanwhile, a new decoherence mechanism caused by new kinds of perturbing magnetic centers is identified below 1.5 K. We further demonstrate the coherent light storage over 5 μμμs by using the atomic frequency comb protocol. These results open up prospects for the realization of practical quantum memories and large scale quantum communications with REI optical ceramics.
Rare earth ions (REI) in solid materials are among the leading systems for quantum technology applications. However, developing practical REI quantum devices with long-lived coherent states remains challenging due to great difficulties in growing high-quality REI materials and incomplete understanding of their decoherence mechanisms. In this work, we report a long optical coherence time of 422 ± 11 μs for the 7F0 → 5D0 transition, as well as a lifetime exceeding 30 hours for the 7F0 hyperfine spin states in Eu3+:Y2O3 optical ceramics. We identify the absence of two-level-system induced optical decoherence in short-range-ordered crystals and a decoherence mechanism caused by perturbing magnetic centers that were not detected previously below 1.5 K. Furthermore, we demonstrate coherent light storage over 5 μs by using the atomic frequency comb protocol. These results provide a promising proof-of-principle demonstration of quantum memory using Eu3+:Y2O3 optical ceramic system, highlighting its significant potential for practical quantum applications. Rare earth ions (REI) in solids are promising for quantum technologies. Here, the authors demonstrate a record optical coherence lifetime and the absence of two-level-system induced decoherence in Eu3+:Y2O3 optical ceramics. These findings advance the optimization of REI-based quantum systems and enable tailored material designs.
Controlled ion-ion interactions and cavity-enhanced emission of a coherent dinuclear Eu3+^{3+}3+ complex
Molecular rare-earth-ion complexes offer unique opportunities for quantum technologies by combining the intrinsic coherence properties of rare-earth ions with chemically tunable molecular environments. A crucial capability is the realization of multi-qubit architectures with defined qubit couplings to enable two-qubit quantum gates. Here, we investigate the optical coherence properties and excitation-induced interactions of two Eu3+^{3+}3+-based molecular complexes, comparing a mononuclear reference system with a dinuclear analogue in which two Eu3+^{3+}3+ ions are positioned at a well-defined intramolecular distance of about 7 Angstrom. Using cryogenic ensemble spectroscopy, including spectral hole burning, free-induction decay, and photon echo measurements at temperatures down to 100 mK, we demonstrate long optical coherence times T2,oT_{2,\text{o}}T2,o​ of up to 9 μμμs. As a key step toward scalable multi-qubit architectures, a control-target sequence was implemented to probe conditional ion-ion interactions, revealing a stronger interaction-induced dephasing in the dinuclear complex. Finally, we show the integration of the dinuclear complex into a fiber-based optical microcavity, and observe an 380-fold emission enhancement of the 5D0→7F0\mathrm{}^5\mathrm{D}_0\rightarrow\mathrm{}^7\mathrm{F}_05D0​→7F0​ transition. Together, these results position molecular rare-earth complexes as versatile and chemically tunable building blocks for scalable quantum technologies.