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Register a new userNanofabricated and integrated colour centres in silicon carbide with high-coherence spin-optical properties
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Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing. Lending themselves to modern semiconductor nanofabrication, they promise scalable high-efficiency spin-photon interfaces. We demonstrate here nanoscale fabrication of silicon vacancy centres (VSi) in 4H-SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly transform limited photon emission and record spin coherence times for single defects generated via ion implantation and in triangular cross section waveguides. For the latter, we show further controlled operations on nearby nuclear spin qubits, which is crucial for fault-tolerant quantum information distribution based on cavity quantum electrodynamics.
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Optically interfaced spins in the solid promise scalable quantum networks. Robust and reliable optical properties have so far been restricted to systems with inversion symmetry. Here, we release this stringent constraint by demonstrating outstanding optical and spin properties of single silicon vacancy centres in silicon carbide. Despite the lack of inversion symmetry, the systems particular wave function symmetry decouples its optical properties from magnetic and electric fields, as well as from local strain. This provides a high-fidelity spin-to-photon interface with exceptionally stable and narrow optical transitions, low inhomogeneous broadening, and a large fraction of resonantly emitted photons. Further, the weak spin-phonon coupling results in electron spin coherence times comparable with nitrogen-vacancy centres in diamond. This allows us to demonstrate coherent hyperfine coupling to single nuclear spins, which can be exploited as qubit memories. Our findings promise quantum network applications using integrated semiconductor-based spin-to-photon interfaces.
Quantum systems combining indistinguishable photon generation and spin-based quantum information processing are essential for remote quantum applications and networking. However, identification of suitable systems in scalable platforms remains a challenge. Here, we investigate the silicon vacancy centre in silicon carbide and demonstrate controlled emission of indistinguishable and distinguishable photons via coherent spin manipulation. Using strong off-resonant excitation and collecting photons from the ultra-stable zero-phonon line optical transitions, we show a two-photon interference contrast close to 90% in Hong-Ou-Mandel type experiments. Further, we exploit the systems intimate spin-photon relation to spin-control the colour and indistinguishability of consecutively emitted photons. Our results provide a deep insight into the systems spin-phonon-photon physics and underline the potential of the industrially compatible silicon carbide platform for measurement-based entanglement distribution and photonic cluster state generation. Additional coupling to quantum registers based on recently demonstrated coupled individual nuclear spins would further allow for high-level network-relevant quantum information processing, such as error correction and entanglement purification.
Spin defects in silicon carbide (SiC) have attracted increasing interests due to their excellent optical and spin properties, which are useful in quantum information processing. In this work, we systematically investigate the temperature dependence of spin properties of divacancy defects in implanted 4H-SiC. The zero-field splitting parameter D, the inhomogeneous dephasing time $T_2^{*}$, the coherence time $T_2$, and the depolarization time $T_1$ are extensively explored in a temperature range from 5 K to 300 K. Two samples implanted with different nitrogen molecule ion fluences ($N_2^{+}$, $10^{14}/rm cm^{2}$ and $10^{13}/rm cm^{2}$) are investigated, whose spin properties are shown to have similar temperature-dependent behaviors. Still, the sample implanted with a lower ion fluence has longer $T_2$ and $T_1$. We provide possible theoretical explanations for the observed temperature-dependent dynamics. Our work promotes the understanding of the temperature dependence of spin properties in solid-state systems, which can be helpful for constructing wide temperature-range thermometers based on the mature semiconductor material.
We discuss the fine structure and spin dynamics of spin-3/2 centers associated with silicon vacancies in silicon carbide. The centers have optically addressable spin states which makes them highly promising for quantum technologies. The fine structure of the spin centers turns out to be highly sensitive to mechanical pressure, external magnetic and electric fields, temperature variation, etc., which can be utilized for efficient room-temperature sensing, particularly by purely optical means or through the optically detected magnetic resonance. We discuss the experimental achievements in magnetometry and thermometry based on the spin state mixing at level anticrossings in an external magnetic field and the underlying microscopic mechanisms. We also discuss spin fluctuations in an ensemble of vacancies caused by interaction with environment.
We study single silicon vacancy (SiV) centres in chemical vapour deposition (CVD) nanodiamonds on iridium as well as an ensemble of SiV centres in a high quality, low stress CVD diamond film by using temperature dependent luminescence spectroscopy in the temperature range 5-295 K. We investigate in detail the temperature dependent fine structure of the zero-phonon-line (ZPL) of the SiV centres. The ZPL transition is affected by inhomogeneous as well as temperature dependent homogeneous broadening and blue shifts by about 20 cm-1 upon cooling from room temperature to 5 K. We employ excitation power dependent g(2) measurements to explore the temperature dependent internal population dynamics of single SiV centres and infer almost temperature independent dynamics.
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