Abstract Solid-state spin–photon interfaces operating in the near-telecom and telecom bands are a key resource for long-distance quantum communication and scalable quantum networks. However, their optical transitions often suffer from spectral diffusion that hampers the generation of coherent spin–photon entanglement. Here we demonstrate narrow magneto-optical transitions of erbium dopants implanted into thin-film silicon carbide (SiC)-on-insulator, a viable platform for industrially scalable quantum networks. Using high-resolution resonant spectroscopy and spectral hole burning at cryogenic temperatures, we reveal sub-megahertz homogeneous linewidths and identify two lattice sites that best stabilise the emitters. We further characterise their optical lifetimes and magneto-optical response, establishing erbium-doped SiC-on-insulator as a robust and scalable platform for on-chip quantum networks.
Abstract Solid-state spin–photon interfaces operating in the near-telecom and telecom bands are a key resource for long-distance quantum communication and scalable quantum networks. However, their optical transitions often suffer from spectral diffusion that hampers the generation of coherent spin–photon entanglement. Here we demonstrate narrow magneto-optical transitions of erbium dopants implanted into thin-film silicon carbide (SiC)-on-insulator, a viable platform for industrially scalable quantum networks. Using high-resolution resonant spectroscopy and spectral hole burning at cryogenic temperatures, we reveal sub-megahertz homogeneous linewidths and identify two lattice sites that best stabilise the emitters. We further characterise their optical lifetimes and magneto-optical response, establishing erbium-doped SiC-on-insulator as a robust and scalable platform for on-chip quantum networks.
Vanadium color centers in silicon carbide (SiC) offer telecom O-band emission, sub-microsecond optical lifetimes, and second-scale spin relaxation times, rendering them promising candidates for quantum network nodes. However, efficient photon extraction from the high-refractive-index SiC host remains challenging. Here, we introduce a silicon-on-SiC heterogeneous photonic platform in which silicon nanocavities evanescently couple to shallow vanadium dopants in commercial 4H-SiC, enabling efficient zero-phonon line (ZPL) collection under resonant excitation. In as-grown ensembles, we observe Purcell-enhanced photoluminescence with transient spectral hole burning linewidths of 50 MHz on microsecond timescales. In dilute implanted samples, we isolate individual vanadium centers with high-purity single photon emission and a Purcell-enhanced lifetime of 109 ns. The entire optical interface operates through a single lensed fiber, including a 905 nm repump laser that recovers the vanadium charge state with 95% efficiency. These results establish Si-on-SiC as a scalable, foundry-compatible platform for telecom-wavelength spin-photon interfaces.
Optically active solid-state spin qubits thrive as an appealing technology for quantum interconnects and quantum networks, thanks to their atomic size, scalable synthesis, long-lived coherence, and ability to coherently interface with flying qubits. Trivalent erbium dopants, in particular, emerge as an attractive candidate due to their emission in the telecom C band and shielded 4f intra-shell spin and optical transitions. Nevertheless, prevailing top-down architectures for rare-earth qubits and devices have not yet achieved simultaneous long optical and spin coherence, which is necessary for efficient long-distance quantum networks. Here, we demonstrate dual Er3+ telecom spin-photon interfaces in two distinct lattice symmetry sites within an epitaxial thin-film platform. By leveraging high matrix crystallinity, controlled proximity of dopants to surfaces, and exploiting host lattice symmetry, we simultaneously achieve kilohertz-level optical linewidth in a strongly symmetry-protected site, and erbium qubit spin coherence times exceeding 10 milliseconds. Additionally, we realize single-shot readout and microwave coherent control of erbium qubits in a fiber-integrated package, enabling rapid deployment and scalability. These advancements highlight the significant potential of high-quality rare-earth qubits and quantum memories assembled using a bottom-up method, paving the way for scalable development of quantum light-matter interfaces tailored for telecommunication quantum networks. Erbium quantum emitters operating in the telecom C band are promising for spin-photon interfaces but achieving both optical and spin coherence has been challenging. Gupta et al. report two types of erbium dopants in epitaxial Y2O3 thin films occupying distinct lattice sites and exhibiting long spin and optical coherence times
Spin-carrying single-photon emitters operating in the telecommunication C-band (1530-1565nm) are prime candidates for integrated spin-photon interfaces, offering seamless compatibility with existing fiber-optic infrastructure, an essential component for future quantum networks. In this context, erbium-dopants (Er3+) are particularly compelling due to their exceptional emitter properties, including small spectral diffusion and long spin coherence times. However, their low C-band photon-emission rate and operation at cryogenic temperatures has limited the realization of this technology.
In this work, we demonstrate fully integrated single-photon emission from an ion implanted Er3+-embedded into a 4H-silicon-carbide-on-insulator (4H-SiCOI) microring resonator operating at room temperature. By optimizing the mode overlap between the resonator and the Er3+-defect, we achieved a $\sim70\times$ Purcell enhancement and recorded small spectral diffusion of $\sim$54 MHz. We further characterize the Er3+ single photon emission via photon correlation g(2)-histograms and investigate its performance under varying magnetic-field, demonstrating Zeeman splitting on single emitters.
Abstract Silicon carbide (SiC) is an excellent industrially compatible material, which has been widely used in high power electronic devices. Recently, spin defects in SiC have been found to be a high-quality spin-to-photon interface with long spin coherence time and high spin-selective optical transition. Spin states can be initialized and readout with extremely high fidelity. The infrared and even telecom fluorescence is suited for fiber communication with less scatting loss. The bandwidth of intrinsic zero-phonon-line emission can be manipulated by classical electrical devices. The achieved near lifetime-limited optical linewidths greatly increase the indistinguishability of photon emission and facilitate the connection with other narrowband absorption quantum systems, such as cold atoms, trapped ions, and rare-earth dopants in crystals. Moreover, spin defects coupled with photonic nanocavities have been demonstrated, which can greatly enhance the photon emission in the zero-phonon-line. The realization of controllable electron-nuclear spin entanglement further extends the memory-based quantum applications. In this perspective, we will briefly discuss the most recent development of spin defects in SiC. These results show that spin defects in SiC are desirable quantum platforms for quantum networking applications. We also discuss some of the current challenges and possible future development.
The realization of a scalable architecture for quantum information processing is a major challenge for quantum science.A promising approach is based on emitters in nanostructures that are coupled by light.Here, we show that erbium dopants can be reproducibly integrated at well-defined lattice sites by implantation into pure silicon.We thus achieve a narrow inhomogeneous broadening, less than 1 GHz, strong optical transitions, and an outstanding optical coherence even at temperatures of 8 K, with an upper bound to the homogeneous linewidth of around 10 kHz.Our study thus introduces a promising materials platform for the implementation of on-chip quantum memories, microwave-to-optical conversion, and distributed quantum information processing.
Abstract Spin-active quantum emitters have emerged as a leading platform for quantum technologies. However, one of their major limitations is the large spread in optical emission frequencies, which typically extends over tens of GHz. Here, we investigate single V 4+ vanadium centres in 4H-SiC, which feature telecom-wavelength emission and a coherent S = 1/2 spin state. We perform spectroscopy on single emitters and report the observation of spin-dependent optical transitions, a key requirement for spin-photon interfaces. By engineering the isotopic composition of the SiC matrix, we reduce the inhomogeneous spectral distribution of different emitters down to 100 MHz, significantly smaller than any other single quantum emitter. Additionally, we tailor the dopant concentration to stabilise the telecom-wavelength V 4+ charge state, thereby extending its lifetime by at least two orders of magnitude. These results bolster the prospects for single V emitters in SiC as material nodes in scalable telecom quantum networks.