arXiv subjects

Qi-Cheng Hu

Publications and source records attributed to Qi-Cheng Hu.

4 recordsLinked to original sources

arXiv2026

Coherent Spin-Photon Interface of single PL6 Color Centers in Silicon Carbide

The PL6 color center in silicon carbide has recently emerged as a promising platform for quantum information processing, yet its coherent spin--photon interface has remained largely unexplored. Here we present a comprehensive investigation of single PL6 centers, combining spectroscopy with theoretical analysis. The excited-state fine structure is fully resolved using group-theoretical modeling and strain-dependent measurements. Under resonant excitation, we achieve a spin initialization fidelity of $99.69 \pm 0.03\%$ and a readout contrast of $98.31 \pm 1.03\%$. The spin--photon--entangled $A_2$ transition exhibits narrow optical linewidths ($\sim 180$~MHz) and a polarization visibility of $\sim 82\%$. Coherent optical driving enables Rabi frequencies up to $2.895$~GHz, while dynamical decoupling extends the spin coherence time from $0.5$~ms to $5.70$~ms. Our results establish PL6 as a competitive solid-state spin--photon interface hosted in a commercially available semiconductor platform.

quant-ph↗

arXiv2025

High-yield engineering and identification of oxygen-related modified divacancies in 4H-SiC

Modified divacancies in the 4H polytype of silicon carbide (SiC) exhibit enhanced charge stability and spin addressability at room temperature, making them attractive for quantum applications. However, their low formation yield and lack of direct structural identification have hindered progress. Here, we demonstrate a controllable method for high-yield engineering and identification of oxygen-related modified divacancy color centers in 4H-SiC via oxygen-ion implantation. Based on their distinct optical and spin-resonance characteristics, we experimentally resolve four types of modified divacancies. Furthermore, by measuring isotope-resolved 17O hyperfine interactions, we identify them as the four crystallographic configurations of oxygen-vacancy (OV) complexes. Remarkably, single OV centers account for over 90% of the total defect population and exhibit superior optical properties and spin coherence compared with defects created by conventional carbon or nitrogen implantation. We characterize the zero-phonon lines of these OV centers and reveal distinct temperature-dependent behavior in spin-readout contrast. By optimizing implantation dose and annealing temperature, we achieve high-density ensembles and observe Rabi-oscillation beating patterns associated with different orientations of basal-type defects. These results establish a high-yield route for scalable engineering of these four oxygen-related modified divacancies in 4H-SiC and clarify their atomic structure, opening new opportunities for solid-state quantum technologies.

quant-ph↗

arXiv2024

Noninvasive magnetic detection of 2D van der Waals room-temperature ferromagnet Fe3GaTe2 using divacancy spins in SiC

Room-temperature (RT) two-dimensional (2D) van der Waals (vdW) ferromagnets hold immense promise for next-generation spintronic devices for information storage and processing. To achieve high-density energy-efficient spintronic devices, it is essential to understand local magnetic properties of RT 2D vdW magnets. In this work, we realize noninvasive in situ magnetic detection in vdW-layered ferromagnet Fe3GaTe2 using divacancy spins quantum sensor in silicon carbide (SiC) at RT. The structural features and magnetic properties of the Fe3GaTe2 are characterized utilizing Raman spectrum, magnetization and magneto-transport measurements. Further detailed analysis of temperature- and magnetic field-dependent optically detected magnetic resonances of the PL6 divacancy near the Fe3GaTe2 reveal that, the Curie temperature (Tc) of Fe3GaTe2 is ~360K, and the magnetization increases with external magnetic fields. Additionally, spin relaxometry technology is employed to probe the magnetic fluctuations of Fe3GaTe2, revealing a peak in the spin relaxation rate around Tc. These experiments give insights into the intriguing local magnetic properties of 2D vdW RT ferromagnet Fe3GaTe2 and pave the way for the application of SiC quantum sensors in noninvasive in situ magnetic detection of related 2D vdW magnets.

quant-ph↗

arXiv2023

High sensitivity silicon carbide divacancy-based thermometer

Color centers in silicon carbide have become potentially versatile quantum sensors. Particularly, wide temperature range temperature sensing has been realized in recent years. However, the sensitivity is limited due to the short dephasing time of the color centers. In this work, we realize a high sensitivity silicon carbide divacancy-based thermometer using the thermal Carr-Purcell-Meiboom-Gill (TCPMG) method. First, the zero field splitting D of PL6 divacancy as a function of temperature is measured with a linear slope of -99.7 kHz/K. The coherence times of TCPMG pulses linearly increase with the pulse number and the longest coherence time is about 21 us, which is ten times larger than dephasing time. The corresponding temperature sensing sensitivity is 13.4 mK/Hz1/2, which is about 15 times higher than previous results. Finally, we monitor the laboratory temperature variations for 24 hours using the TCMPG pulse. The experiments pave the way for the applications of silicon carbide-based high sensitivity thermometer in the semiconductor industry, biology, and materials sciences.

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