Microwave-Based Quantum Control and Coherence Protection of Tin-Vacancy Spin Qubits in a Strain-Tuned Diamond-Membrane Heterostructure
Xinghan Guo, Alexander M. Stramma, Zixi Li, William G. Roth, Benchen Huang, Yu Jin, Ryan A. Parker, Jesús Arjona Martínez, Noah Shofer, Cathryn P. Michaels, Carola P. Purser, Martin Hayhurst Appel, Evgeny M. Alexeev, Tianle Liu, Andrea Carlo Ferrari, D. D. Awschalom, Nazar Delegan, Benjamin Pingault, Giulia Galli, F. Joseph Heremans, Mete Atatüre, Alexander A. High
Robust spin-photon interfaces in solids are essential components in quantum networking and sensing technologies. Ideally, these interfaces combine a long-lived spin memory, coherent optical transitions, fast and high-fidelity spin manipulation, and straightforward device integration and scaling. The tinvacancy center (SnV) in diamond is a promising spin-photon interface with desirable optical and spin properties at 1.7 K. However, the SnV spin lacks efficient microwave control, and its spin coherence degrades with higher temperature. In this work, we introduce a new platform that overcomes these challenges—SnV centers in uniformly strained thin diamond membranes. The controlled generation of crystal strain introduces orbital mixing that allows microwave control of the spin state with 99.36(9)% gate fidelity and spin coherence protection beyond a millisecond. Moreover, the presence of crystal strain suppresses temperature-dependent dephasing processes, leading to a considerable improvement of the coherence time up to 223(10) μs at 4 K, a widely accessible temperature in common cryogenic systems. Critically, the coherence of optical transitions is unaffected by the elevated temperature, exhibiting nearly lifetime-limited optical linewidths. Combined with the compatibility of diamond membranes with device integration, the demonstrated platform is an ideal spin-photon interface for future quantum technologies.
Robust spin-photon interfaces in solids are essential components in quantum networking and sensing technologies. Ideally, these interfaces combine a long-lived spin memory, coherent optical transitions, fast and high-fidelity spin manipulation, and straightforward device integration and scaling. The tinvacancy center (SnV) in diamond is a promising spin-photon interface with desirable optical and spin properties at 1.7 K. However, the SnV spin lacks efficient microwave control, and its spin coherence degrades with higher temperature. In this work, we introduce a new platform that overcomes these challenges—SnV centers in uniformly strained thin diamond membranes. The controlled generation of crystal strain introduces orbital mixing that allows microwave control of the spin state with 99.36(9)% gate fidelity and spin coherence protection beyond a millisecond. Moreover, the presence of crystal strain suppresses temperature-dependent dephasing processes, leading to a considerable improvement of the coherence time up to 223(10) μs at 4 K, a widely accessible temperature in common cryogenic systems. Critically, the coherence of optical transitions is unaffected by the elevated temperature, exhibiting nearly lifetime-limited optical linewidths. Combined with the compatibility of diamond membranes with device integration, the demonstrated platform is an ideal spin-photon interface for future quantum technologies.
Robust spin-photon interfaces in solids are essential components in quantum networking and sensing technologies.Ideally, these interfaces combine a long-lived spin memory, coherent optical transitions, fast and high-fidelity spin manipulation, and straightforward device integration and scaling.The tinvacancy center (SnV) in diamond is a promising spin-photon interface with desirable optical and spin properties at 1.7 K.However, the SnV spin lacks efficient microwave control, and its spin coherence degrades with higher temperature.In this work, we introduce a new platform that overcomes these challenges-SnV centers in uniformly strained thin diamond membranes.The controlled generation of crystal strain introduces orbital mixing that allows microwave control of the spin state with 99.36(9)% gate fidelity and spin coherence protection beyond a millisecond.Moreover, the presence of crystal strain suppresses temperature-dependent dephasing processes, leading to a considerable improvement of the coherence time up to 223ð10Þ μs at 4 K, a widely accessible temperature in common cryogenic systems.Critically, the coherence of optical transitions is unaffected by the elevated temperature, exhibiting nearly lifetime-limited optical linewidths.Combined with the compatibility of diamond membranes with device integration, the demonstrated platform is an ideal spin-photon interface for future quantum technologies.
Group-IV color centers in diamond are promising candidates for quantum networks due to their dominant zero-phonon line and symmetry-protected optical transitions that connect to coherent spin levels. The negatively charged tin-vacancy (SnV) center possesses long electron spin lifetimes due to its large spin-orbit splitting. However, the magnetic dipole transitions required for microwave spin control are suppressed, and strain is necessary to enable these transitions. Recent work has shown spin control of strained emitters using microwave lines that suffer from Ohmic losses, restricting coherence through heating. We utilize a superconducting coplanar waveguide to measure SnV centers subjected to strain, observing substantial improvement. A detailed analysis of the SnV center electron spin Hamiltonian based on the angle-dependent splitting of the ground and excited states is performed. We demonstrate coherent spin manipulation and obtain a Hahn echo coherence time of up to T 2 = 430 μ s . With dynamical decoupling, we can prolong coherence to T 2 = 10 ms , about a sixfold improvement compared to earlier works. We also observe a nearby coupling C 13 spin, which may serve as a quantum memory, thus substantiating the potential of SnV centers in diamond and demonstrates the benefit of superconducting microwave structures. 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.
The realization of quantum networks critically depends on establishing efficient, coherent light-matter interfaces. Optically active spins in diamond have emerged as promising quantum nodes based on their spin-selective optical transitions, long-lived spin ground states, and potential for integration with nanophotonics. Tin-vacancy (SnV-) centers in diamond are of particular interest because they exhibit narrow-linewidth emission in nanostructures and possess long spin coherence times at temperatures above 1 K. However, a nanophotonic interface for SnV- centers has not yet been realized. Here, we report cavity enhancement of the emission of SnV- centers in diamond. We integrate SnV- centers into one-dimensional photonic crystal resonators and observe a 40-fold increase in emission intensity. The Purcell factor of the coupled system is 25, resulting in channeling of the majority of photons (90%) into the cavity mode. Our results pave the way for the creation of efficient, scalable spin-photon interfaces based on SnV- centers in diamond.
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
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.