| 1. |
- Astner, Thomas, et al.
(author)
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Vanadium in silicon carbide: telecom-ready spin centres with long relaxation lifetimes and hyperfine-resolved optical transitions
- 2024
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In: QUANTUM SCIENCE AND TECHNOLOGY. - : IOP Publishing Ltd. - 2058-9565. ; 9:3
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Journal article (peer-reviewed)abstract
- Vanadium in silicon carbide (SiC) is emerging as an important candidate system for quantum technology due to its optical transitions in the telecom wavelength range. However, several key characteristics of this defect family including their spin relaxation lifetime (T1), charge state dynamics, and level structure are not fully understood. In this work, we determine the T1 of an ensemble of vanadium defects, demonstrating that it can be greatly enhanced at low temperature. We observe a large spin contrast exceeding 90% and long spin-relaxation times of up to 25 s at 100 mK, and of order 1 s at 1.3 K. These measurements are complemented by a characterization of the ensemble charge state dynamics. The stable electron spin furthermore enables high-resolution characterization of the systems' hyperfine level structure via two-photon magneto-spectroscopy. The acquired insights point towards high-performance spin-photon interfaces based on vanadium in SiC.
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| 2. |
- Bosma, Tom, et al.
(author)
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Identification and tunable optical coherent control of transition-metal spins in silicon carbide
- 2018
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In: NPJ QUANTUM INFORMATION. - : SPRINGERNATURE. - 2056-6387. ; 4
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Journal article (peer-reviewed)abstract
- Color centers in wide-bandgap semiconductors are attractive systems for quantum technologies since they can combine long-coherent electronic spin and bright optical properties. Several suitable centers have been identified, most famously the nitrogen-vacancy defect in diamond. However, integration in communication technology is hindered by the fact that their optical transitions lie outside telecom wavelength bands. Several transition-metal impurities in silicon carbide do emit at and near telecom wavelengths, but knowledge about their spin and optical properties is incomplete. We present all-optical identification and coherent control of molybdenum-impurity spins in silicon carbide with transitions at near-infrared wavelengths. Our results identify spin S= 1/2 for both the electronic ground and excited state, with highly anisotropic spin properties that we apply for implementing optical control of ground-state spin coherence. Our results show optical lifetimes of similar to 60 ns and inhomogeneous spin dephasing times of similar to 0.3 mu S, establishing relevance for quantum spin-photon interfacing.
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| 3. |
- Gilardoni, Carmem M., et al.
(author)
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Spin-relaxation times exceeding seconds for color centers with strong spin-orbit coupling in SiC
- 2020
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In: New Journal of Physics. - : IOP PUBLISHING LTD. - 1367-2630. ; 22:10
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Journal article (peer-reviewed)abstract
- Spin-active color centers in solids show good performance for quantum technologies. Several transition-metal defects in SiC offer compatibility with telecom and semiconductor industries. However, whether their strong spin-orbit coupling degrades their spin lifetimes is not clear. We show that a combination of a crystal-field with axial symmetry and spin-orbit coupling leads to a suppression of spin-lattice and spin-spin interactions, resulting in remarkably slow spin relaxation. Our optical measurements on an ensemble of Mo impurities in SiC show a spin lifetime T-1 of 2.4 s at 2 K.
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| 4. |
- Zwier, Olger V, et al.
(author)
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Electromagnetically induced transparency in inhomogeneously broadened divacancy defect ensembles in SiC
- 2022
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 131:9
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Journal article (peer-reviewed)abstract
- Electromagnetically induced transparency (EIT) is a phenomenon that can provide strong and robust interfacing between optical signals and quantum coherence of electronic spins. In its archetypical form, mainly explored with atomic media, it uses a (near-)homogeneous ensemble of three-level systems, in which two low-energy spin-1/2 levels are coupled to a common optically excited state. We investigate the implementation of EIT with c-axis divacancy color centers in silicon carbide. While this material has attractive properties for quantum device technologies with near-IR optics, implementing EIT is complicated by the inhomogeneous broadening of the optical transitions throughout the ensemble and the presence of multiple ground-state levels. These may lead to darkening of the ensemble upon resonant optical excitation. Here, we show that EIT can be established with high visibility also in this material platform upon careful design of the measurement geometry. Comparison of our experimental results with a model based on the Lindblad equations indicates that we can create coherences between different sets of two levels all-optically in these systems, with potential impact for RF-free quantum sensing applications. Our work provides an understanding of EIT in multi-level systems with significant inhomogeneities, and our considerations are valid for a wide array of defects in semiconductors. Published under an exclusive license by AIP Publishing.
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