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arXiv:2601.21499

RF-free driving of nuclear spins with color centers in silicon carbide

Raphael Wörnle, Jonathan Körber, Timo Steidl, Georgy V. Astakhov, Durga B. R. Dasari, Florian Kaiser, Vadim Vorobyov, Jörg Wrachtrup

quant-phSubmitted Jan 29, 2026• Announced Jan 30, 2026
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Abstract

Color centers that enable nuclear-spin control without RF fields offer a powerful route towards simplified and scalable quantum devices. Such capabilities are especially valuable for quantum sensing and computing platforms that already find applications in biology, materials science, and geophysics. A key challenge is the coherent manipulation of nearby nuclear spins, which serve as quantum memories and auxiliary qubits but conventionally require additional high-power RF fields which increase the experimental complexity and overall power consumption. Finding systems where both electron and nuclear spins can be controlled using a single MW source is therefore highly desirable. Here, using a modified divacancy center in silicon carbide, we show that coherent control of a coupled nuclear spin is possible without any RF fields. Instead, MW pulses driving the electron spin also manipulate the nuclear spin through hyperfineenhanced effects, activated by a precisely tilted external magnetic field. We demonstrate high-fidelity nuclear-spin control, achieving 89% two-qubit tomography fidelity and nearly T1-limited nuclear coherence times. This approach offers a simplified and scalable route for future quantum applications.

Related papers

Scalable Quantum Memory Nodes using nuclear spins in Silicon Carbide

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The ultimate motivation of my project is to address the possibility of building a quantum analogue of Internet of Things in order to improve the standards of quantum information processing. A distributed quantum computing network which is capable of achieving this goal, would require large sets of memory nodes capable of performing arbitrary quantum information protocols with high fidelity [1], [2]. So far, the challenge in this field has been in realizing such quantum memory nodes with features for scalable quantum computing. Solid state spins in 4H-Silicon Carbide (4H-SiC) owing to its material properties provides a suitable platform in achieving this goal wherein a controlled generation of highly coherent qubit registers using nuclear spins$(^{13}\mathrm{C} \ \text{or} \ {}^{\text{29}} \text{Si})$and silicon vacancy color centers$(V_{Si}^{-} \ \text{center})$| are possible[3], [4]. The magnetic dipole-dipole coupling between the isotope nuclear spins and the silicon vacancy color center can be tapped using microwave pulse (MW) sequence (as shown in Fig. 1(a)) for controlled driving of nuclear spin.

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Scalable quantum memory nodes using nuclear spins in Silicon Carbide

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A distributed quantum network would require quantum nodes capable of performing arbitrary quantum information protocols with high fidelity. So far the challenge has been in realizing such quantum nodes with features for scalable quantum computing. We show here that using the solid-state spins in 4H-Silicon Carbide (4H-SiC) such a goal could be realized, wherein a controlled generation of highly coherent qubit registers using nuclear spins is possible. Using a controlled isotope concentration and coherent control we perform here atomistic modeling of the central spin system formed by the electron spin of a silicon vacancy color center ($V_{Si}^-$-center) and the non-interacting nuclear spins. From this we lay out conditions for realizing a scalable nuclear-spin ($^{13}C$ or $^{29}Si$) register, wherein independent control of the qubits alongside their mutual controlled operations using the central electron spin associated to the $V_{Si}^-$-center in 4H-SiC are achieved. Further, the decoherence and entanglement analysis provided here could be used to evaluate the quantum volume of these nodes. Our results mark a clear route towards realizing scalable quantum memory nodes for applications in distributed quantum computing networks and further for quantum information protocols.

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Optically addressable spin defects are excellent candidate platform for quantum sensing and quantum network. Nuclear spins coupled to color centers naturally enable long lived quantum memories and local qubits registers. To fully leverage this potential precise characterization of the surrounding nuclear-spin environment augmented with refined DFT models is required. In this work, we report angstrom-level 3D localization of 25 nuclear spins around a single V2 center in 4H Silicon Carbide. Utilizing specially placed robust nuclear memory as a highly efficient readout ancilla for readout, we apply correlation based spectroscopy and by selecting multi-spin chains up to length four, we access and characterize extended nuclear spin cluster. Using the coupling map we reconstruct their couplings to the central electron spin and neighboring nuclei. This work paves the way towards advanced quantum register applications on Silicon Carbide platform.

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Florian Kaiser

We highlight our work [1] on nanophotonic integration of color centers in semiconductor silicon carbide (SiC). We show ion-assisted implantation and waveguide-integration of silicon vacancy centers (VSi) in 4H-SiC with nearly lifetime limited optical lines and record spin coherence times. We further show controlled coupling to nearby nuclear spin qubits. Our experiments can be performed at high temperatures (T=20 K), thus enabling fast and direct nuclear spin control. Our work shows that VSi centers in SiC are attractive for developing next-generation quantum (computational) networks based on optically interconnected spin-based qubit clusters. [1] Babin et al, Nature Materials, to appear (2021)

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Robust entanglement at room temperature is a central challenge for solid-state quantum information processing and quantum-enhanced sensing. Here we demonstrate room-temperature storage of entanglement in a silicon carbide (SiC) quantum node by coherently transferring an electron-nuclear entangled state onto long-lived nuclear-spin memory qubits. Using a shallow single color center in 4H-SiC, conventionally denoted PL6, we realize a fully addressable three-qubit register composed of one electron-spin processor and two strongly coupled $^{29}$Si nuclear-spin memory qubits. This platform enables the deterministic generation of high-fidelity entangled states, including a nuclear-spin Bell state with a fidelity of $94 \pm 2\%$ and a three-qubit Greenberger-Horne-Zeilinger (GHZ)-type state with a fidelity of $89 \pm 4\%$. By implementing a SWAP-gate protocol in the strong hyperfine-coupling regime, the electron-nuclear entanglement is transferred to the nuclear-spin memory with a fidelity of $92.5 \pm 2.5\%$, extending the entanglement lifetime by a factor of 240. We further confirm the generality of this approach in an additional heterogeneous $^{29}$Si-$^{13}$C nuclear-spin register and, through a statistical survey of 200 single PL6 centers, show that multi-nuclear-spin registers occur naturally with probabilities above 10%. These results position shallow SiC color centers as a powerful platform for entanglement-assisted quantum sensing and scalable room-temperature quantum technologies.

quant-pharXiv:2609.13744•Physical Review Letters•Sep 15, 2026•0 citations

Hybrid dynamical decoupling and coherent driving for high-fidelity nuclear-spin control in diamond

Jiwon Jeon, Donghun Jung, Eunsang Lee +1 more

Nitrogen-vacancy (NV) centers in diamond provide room-temperature electron-nuclear spin registers for quantum sensing and quantum information processing, with surrounding 13C nuclear spins serving as long-lived quantum memories. However, coherent control of large nuclear-spin registers is limited by finite electron-spin coherence and spectral addressability. Existing approaches follow two complementary strategies: dynamical-decoupling (DD) gates exploit filter-function resonances to realize selective conditional evolution but permit only discrete rotation angles, whereas dynamical-decoupling radio-frequency (DDrf) control restores continuous tunability at the cost of stringent hyperfine-geometry and RF-power requirements. Here, we introduce hybrid dynamical-decoupling and radio-frequency (H-DDrf) control, which preserves the DD-induced conditional evolution and employs a geometrically phase-matched RF drive to complete the target operation. This approach reduces both RF power and gate duration while maintaining high-fidelity control, thereby expanding the accessible 13C nuclear-spin register for room-temperature NV-based quantum memories and quantum processors.

quant-pharXiv:2608.20742•Aug 24, 2026•0 citations
Color centers that enable nuclear-spin control without RF fields offer a powerful route towards simplified and scalable quantum devices. Such capabilities are especially valuable for quantum sensing and computing platforms that already find applications in biology, materials science, and geophysics. A key challenge is the coherent manipulation of nearby nuclear spins, which serve as quantum memories and auxiliary qubits but conventionally require additional high-power RF fields which increase the experimental complexity and overall power consumption. Finding systems where both electron and nuclear spins can be controlled using a single MW source is therefore highly desirable. Here, using a modified divacancy center in silicon carbide, we show that coherent control of a coupled nuclear spin is possible without any RF fields. Instead, MW pulses driving the electron spin also manipulate the nuclear spin through hyperfineenhanced effects, activated by a precisely tilted external magnetic field. We demonstrate high-fidelity nuclear-spin control, achieving 89% two-qubit tomography fidelity and nearly T1-limited nuclear coherence times. This approach offers a simplified and scalable route for future quantum applications.
The ultimate motivation of my project is to address the possibility of building a quantum analogue of Internet of Things in order to improve the standards of quantum information processing. A distributed quantum computing network which is capable of achieving this goal, would require large sets of memory nodes capable of performing arbitrary quantum information protocols with high fidelity [1], [2]. So far, the challenge in this field has been in realizing such quantum memory nodes with features for scalable quantum computing. Solid state spins in 4H-Silicon Carbide (4H-SiC) owing to its material properties provides a suitable platform in achieving this goal wherein a controlled generation of highly coherent qubit registers using nuclear spins(13C or 29Si)(^{13}\mathrm{C} \ \text{or} \ {}^{\text{29}} \text{Si})(13C or 29Si)and silicon vacancy color centers(VSi− center)(V_{Si}^{-} \ \text{center})(VSi−​ center)| are possible[3], [4]. The magnetic dipole-dipole coupling between the isotope nuclear spins and the silicon vacancy color center can be tapped using microwave pulse (MW) sequence (as shown in Fig. 1(a)) for controlled driving of nuclear spin.
A distributed quantum network would require quantum nodes capable of performing arbitrary quantum information protocols with high fidelity. So far the challenge has been in realizing such quantum nodes with features for scalable quantum computing. We show here that using the solid-state spins in 4H-Silicon Carbide (4H-SiC) such a goal could be realized, wherein a controlled generation of highly coherent qubit registers using nuclear spins is possible. Using a controlled isotope concentration and coherent control we perform here atomistic modeling of the central spin system formed by the electron spin of a silicon vacancy color center (VSi−V_{Si}^-VSi−​-center) and the non-interacting nuclear spins. From this we lay out conditions for realizing a scalable nuclear-spin (13C^{13}C13C or 29Si^{29}Si29Si) register, wherein independent control of the qubits alongside their mutual controlled operations using the central electron spin associated to the VSi−V_{Si}^-VSi−​-center in 4H-SiC are achieved. Further, the decoherence and entanglement analysis provided here could be used to evaluate the quantum volume of these nodes. Our results mark a clear route towards realizing scalable quantum memory nodes for applications in distributed quantum computing networks and further for quantum information protocols.
Optically addressable spin defects are excellent candidate platform for quantum sensing and quantum network. Nuclear spins coupled to color centers naturally enable long lived quantum memories and local qubits registers. To fully leverage this potential precise characterization of the surrounding nuclear-spin environment augmented with refined DFT models is required. In this work, we report angstrom-level 3D localization of 25 nuclear spins around a single V2 center in 4H Silicon Carbide. Utilizing specially placed robust nuclear memory as a highly efficient readout ancilla for readout, we apply correlation based spectroscopy and by selecting multi-spin chains up to length four, we access and characterize extended nuclear spin cluster. Using the coupling map we reconstruct their couplings to the central electron spin and neighboring nuclei. This work paves the way towards advanced quantum register applications on Silicon Carbide platform.
We highlight our work [1] on nanophotonic integration of color centers in semiconductor silicon carbide (SiC). We show ion-assisted implantation and waveguide-integration of silicon vacancy centers (VSi) in 4H-SiC with nearly lifetime limited optical lines and record spin coherence times. We further show controlled coupling to nearby nuclear spin qubits. Our experiments can be performed at high temperatures (T=20 K), thus enabling fast and direct nuclear spin control. Our work shows that VSi centers in SiC are attractive for developing next-generation quantum (computational) networks based on optically interconnected spin-based qubit clusters. [1] Babin et al, Nature Materials, to appear (2021)
Robust entanglement at room temperature is a central challenge for solid-state quantum information processing and quantum-enhanced sensing. Here we demonstrate room-temperature storage of entanglement in a silicon carbide (SiC) quantum node by coherently transferring an electron-nuclear entangled state onto long-lived nuclear-spin memory qubits. Using a shallow single color center in 4H-SiC, conventionally denoted PL6, we realize a fully addressable three-qubit register composed of one electron-spin processor and two strongly coupled 29^{29}29Si nuclear-spin memory qubits. This platform enables the deterministic generation of high-fidelity entangled states, including a nuclear-spin Bell state with a fidelity of 94±2%94 \pm 2\%94±2% and a three-qubit Greenberger-Horne-Zeilinger (GHZ)-type state with a fidelity of 89±4%89 \pm 4\%89±4%. By implementing a SWAP-gate protocol in the strong hyperfine-coupling regime, the electron-nuclear entanglement is transferred to the nuclear-spin memory with a fidelity of 92.5±2.5%92.5 \pm 2.5\%92.5±2.5%, extending the entanglement lifetime by a factor of 240. We further confirm the generality of this approach in an additional heterogeneous 29^{29}29Si-13^{13}13C nuclear-spin register and, through a statistical survey of 200 single PL6 centers, show that multi-nuclear-spin registers occur naturally with probabilities above 10%. These results position shallow SiC color centers as a powerful platform for entanglement-assisted quantum sensing and scalable room-temperature quantum technologies.
Nitrogen-vacancy (NV) centers in diamond provide room-temperature electron-nuclear spin registers for quantum sensing and quantum information processing, with surrounding 13C nuclear spins serving as long-lived quantum memories. However, coherent control of large nuclear-spin registers is limited by finite electron-spin coherence and spectral addressability. Existing approaches follow two complementary strategies: dynamical-decoupling (DD) gates exploit filter-function resonances to realize selective conditional evolution but permit only discrete rotation angles, whereas dynamical-decoupling radio-frequency (DDrf) control restores continuous tunability at the cost of stringent hyperfine-geometry and RF-power requirements. Here, we introduce hybrid dynamical-decoupling and radio-frequency (H-DDrf) control, which preserves the DD-induced conditional evolution and employs a geometrically phase-matched RF drive to complete the target operation. This approach reduces both RF power and gate duration while maintaining high-fidelity control, thereby expanding the accessible 13C nuclear-spin register for room-temperature NV-based quantum memories and quantum processors.