Abstract The recently discovered negatively charged tin-vacancy centre in diamond is a promising candidate for applications in quantum information processing (QIP). We here present a detailed spectroscopic study encompassing single photon emission and polarisation properties, the temperature dependence of emission spectra as well as a detailed analysis of the phonon sideband and Debye–Waller factor. Using photoluminescence excitation spectroscopy we probe an energetically higher lying excited state and prove fully lifetime limited linewidths of single emitters at cryogenic temperatures. For these emitters we also investigate the stability of the charge state under resonant excitation. These results provide a detailed insight into the spectroscopic properties of the SnV− centre and lay the foundation for further studies regarding its suitability in QIP.
The negatively charged tin-vacancy center in diamond (SnV−) is a highly promising candidate for next-generation long-distance quantum networks, owing to its bright emission, robustness against electronic noise, and extended spin coherence times at higher temperatures. We demonstrate the measurement of a single SnV− electronic spin with a single-shot readout fidelity of 87.4%, which can be further enhanced to 98.5% using conditional readout. Our findings show that SnV− centers are compatible with rapid microwave spin control, overcoming the typical trade-off between optical readout and spin control found in group-IV centers in diamond. Additionally, we investigate measurement-induced dephasing through weak quantum measurement, shedding light on the fundamental interplay between measurement and decoherence in quantum mechanics, and utilizing the qubit’s spin coherence as a metrological tool. These advancements represent a significant milestone in SnV− based quantum technologies, providing techniques and insights widely applicable to solid-state quantum emitters.
The negatively charged tin-vacancy center in diamond ( SnV − ) is an emerging platform for building the next generation of long-distance quantum networks. This is due to the SnV − ’s favorable optical and spin properties including bright emission, insensitivity to electronic noise, and long spin coherence times at temperatures above 1 K. Here, we demonstrate measurement of a single SnV − electronic spin with a single-shot readout fidelity of 87.4%, which can be further improved to 98.5% by conditioning on multiple readouts. In the process, we develop understanding of the relationship between strain, magnetic field, spin readout, and microwave spin control. We show that high-fidelity readout is compatible with rapid microwave spin control, demonstrating a favorable parameter regime for use of the SnV − center as a high-quality spin-photon interface. Finally, we use weak quantum measurement to study measurement-induced dephasing; this illuminates the fundamental interplay between measurement and decoherence in quantum mechanics, and provides a universal method to characterize the efficiency of color-center spin readout. Taken together, these results overcome an important hurdle in the development of the SnV − -based quantum technologies and, in the process, develop techniques and understanding broadly applicable to the study of solid-state quantum emitters. Published by the American Physical Society 2024
Group-IV color centers in diamond are a promising light-matter interface for quantum networking devices.The negatively charged tin-vacancy center (SnV) is particularly interesting, as its large spin-orbit coupling offers strong protection against phonon dephasing and robust cyclicity of its optical transitions toward spin-photon-entanglement schemes.Here, we demonstrate multiaxis coherent control of the SnV spin qubit via an all-optical stimulated Raman drive between the ground and excited states.We use coherent population trapping and optically driven electronic spin resonance to confirm coherent access to the qubit at 1.7 K and obtain spin Rabi oscillations at a rate of Ω=2π ¼ 19.0ð1Þ MHz.All-optical Ramsey interferometry reveals a spin dephasing time of T Ã 2 ¼ 1.3ð3Þ μs, and four-pulse dynamical decoupling already extends the spin-coherence time to T 2 ¼ 0.30ð8Þ ms.Combined with transform-limited photons and integration into photonic nanostructures, our results make the SnV a competitive spin-photon building block for quantum networks.
Atomic defects in solids offer access to atom-like quantum properties without complex trapping methods while displaying a rich physics due to interactions with their solid-state environment. Such properties have made them an advantageous building block for quantum information processing, in particular to construct a quantum network, where information would be encoded in spins and transferred between nodes through photons. Among defects in solids, the negatively charged silicon-vacancy centre in diamond (SiV
−) has attracted attention for its very promising optical properties for such a network. In this thesis, we investigate the spin properties of the silicon-vacancy centre as a potential spin-photon interface. First, we use resonant excitation of an SiV
− centre in an external magnetic field to selectively address different electronic states and analyse the resulting fluorescence. We find evidence of selection rules in the optical transitions revealing that the centre possesses an electronic spin S = 1/2. Making use of the dependence of such selection rules on the applied magnetic field orientation, we resonantly drive two optical transitions forming a
Λ-scheme. In the double resonance condition, we achieve coherent population trapping, whereby the SiV
− is pumped into a dark state corresponding to a superposition of the two addressed ground states of opposite spin. This technique allows us to evaluate the coherence time of the dark state and hence of the spin, while demonstrating the possibility of all-optical control of the spin when a
Λ-scheme is available. We then use resonant optical pulses to initialise and read out the spin state of a single SiV
−. By tuning a microwave pulse into resonance between two ground states of opposite spin, we demonstrate optically detected magnetic resonance. Subsequently, by varying the duration of a resonant microwave pulse, we achieve coherent control of a single SiV
− electronic spin. Through Ramsey interferometry, we measure a spin dephasing time of 115
± 9 ns. We then investigate interactions of the SiV
− with its environment. We analyse the hyperfine interaction of the SiV
− spin with the nuclear spin of
29Si, with a view to taking advantage of the long-lived nuclear spin in the future. We show that single-phonon-mediated excitations between electronic states of the SiV
− are the dominant spin dephasing and population decay mechanism and evaluate how external strain alters optical selection rules and can be used to improve the coherence time of the spin.
The negatively charged silicon-vacancy (SiV^{-}) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date (∼250 ns) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV^{-} electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV^{-} symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV^{-} spin with 89% fidelity. Coherent control of the SiV^{-} spin with microwave fields is used to demonstrate a spin coherence time T_{2} of 13 ms and a spin relaxation time T_{1} exceeding 1 s at 100 mK. These results establish the SiV^{-} as a promising solid-state candidate for the realization of quantum networks.