- The paper demonstrates the isolation of single-electron spins in 4H-SiC with a Hahn-echo coherence time of 1.25 ms, exceeding previous metrics without advanced decoupling.
- It employs hot-wall chemical vapor deposition to fabricate 120-micron-thick epitaxial SiC films with minimal defect densities, enabling precise spin control.
- The findings highlight significant potential for quantum information processing and nanoscale sensing due to the scalable integration of SiC in semiconductor technologies.
Electron Spin Coherence in Silicon Carbide
This paper presents significant advancements in isolating and controlling individual electron spin states bound to neutral divacancy defects in highly purified monocrystalline 4H-silicon carbide (SiC). The research demonstrates the potential of these isolated electron spins for quantum information and nanoscale sensing applications, showcasing over millisecond-long Hahn-echo spin coherence times in SiC, a material conducive to advanced growth and microfabrication methods.
The study addresses the limitations of previous works on SiC for optically detected magnetic resonance (ODMR), which were confined to measuring spin ensembles rather than individual electronic states. By employing hot-wall chemical vapor deposition, the researchers achieved highly purified SiC substrates with negligible defect densities, enabling the isolation of single-electron spins. The paper details the growth of a 120-micron-thick single-crystal epitaxial film on an n-type 4H-SiC substrate, subsequently irradiated and annealed to form divacancies active in spin manipulation.
A critical finding is that the Hahn-echo spin coherence time (T2) of isolated divacancies reached (1.25 ± 0.05) milliseconds, substantially exceeding previous values of 360 microseconds for SiC with higher defect densities and 600 microseconds for NV centers in chemically purified diamond. The paper argues that this coherence time, achieved without isotopic purification or advanced dynamical decoupling sequences, signifies a major advancement in single-spin coherency attainable in a scalable material like SiC.
The authors present robust quantitative results with a strong emphasis on optical measurements for assessing single divacancy properties. They demonstrate ODMR, showing spin transitions via changes in photoluminescence (PL), and observe Rabi oscillations, indicating coherent control of electron spins. Notably, diverse divacancy configurations are explored, like the (hh), (kk), and (kh) forms, while the (hk) configuration is less stable, possibly due to disparate formation energies.
The implications of these findings extend to both practical and theoretical domains. Practically, the long coherence times and single-spin addressability in a scalable semiconductor like SiC holds promise for developing quantum-repeater networks, with potential telecommunications applications due to near-infrared divacancy emission. Furthermore, potential engineering of SiC devices incorporating spin-based sensors and memories is envisioned, with prospects for electrostatically controlled spin-spin interactions and studying spin-phonon dynamics in high-Q micromechanical resonators.
Theoretically, the demonstration of coherent single-spin control in SiC suggests new avenues for exploring spin-based quantum computing and advanced quantum error correction techniques. Future research could focus on isotopic purification to further extend coherence times and explore new quantum control and entanglement schemes within SiC platforms. These developments could pave the way for integrating quantum and classical computing technologies, thus enhancing the performance and functionality of existing electronic devices.
In conclusion, this work underscores the viability of silicon carbide as a potential medium for advanced quantum information processing, positioning it alongside other promising materials like diamond, but with unique advantages in scalability and integration with existing semiconductor technologies.
