MRI技術を応用した量子技術開発：2D材料の応用研究（MRI technology inspires quantum advancement with 2D materials）

2025-08-27 パデュー大学

パデュー大学の研究チームは、MRIやNMR（核磁気共鳴）の原理を応用し、二次元材料上で単一原子スピンを検出・制御できる新しい量子センシング技術を開発した。従来のNMRは大量分子の平均的信号しか得られなかったが、本研究では六方窒化ホウ素（hBN）に導入した欠陥原子を量子センサーとして利用し、原子スケールでの核スピン信号を光学的に読み取ることに成功した。これにより、原子1個単位のNMR分光を実現し、極めて高感度な分子構造解析が可能となった。さらに、この「光検出型NMR（ODNMR）」手法は量子情報処理や高分解能材料分析への応用が期待され、従来のMRI技術をナノスケールに拡張する画期的成果と位置づけられる。研究は米国エネルギー省などの支援を受け、『Nature Nanotechnology』誌に掲載。

＜関連情報＞

ファンデルワールス物質における単一核スピンの検出と制御 Single nuclear spin detection and control in a van der Waals material

Xingyu Gao,Sumukh Vaidya,Kejun Li,Zhun Ge,Saakshi Dikshit,Shimin Zhang,Peng Ju,Kunhong Shen,Yuanbin Jin,Yuan Ping & Tongcang Li
Nature Published:09 July 2025
DOI:https://doi.org/10.1038/s41586-025-09258-7

Abstract

Optically active spin defects in solids^1,2 are leading candidates for quantum sensing^3,4 and quantum networking^5,6. Recently, single spin defects were discovered in hexagonal boron nitride (hBN)^7,8,9,10,11, a layered van der Waals (vdW) material. Owing to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale quantum sensing¹², including nuclear magnetic resonance (NMR) of single molecules. However, the chemical structures of these defects^7,8,9,10,11 remain unknown and detecting a single nuclear spin with a hBN spin defect has been elusive. Here we report the creation of single spin defects in hBN using ¹³C ion implantation and the identification of three distinct defect types based on hyperfine interactions. We observed both S = 1/2 and S = 1 spin states within a single hBN spin defect. We demonstrated atomic-scale NMR and coherent control of individual nuclear spins in a vdW material, with a π-gate fidelity up to 99.75% at room temperature. By comparing experimental results with density functional theory (DFT) calculations, we propose chemical structures for these spin defects. Our work advances the understanding of single spin defects in hBN and provides a pathway to enhance quantum sensing using hBN spin defects with nuclear spins as quantum memories.

六方晶窒化ホウ素における核スピン偏極と制御 Nuclear spin polarization and control in hexagonal boron nitride

Xingyu Gao,Sumukh Vaidya,Kejun Li,Peng Ju,Boyang Jiang,Zhujing Xu,Andres E. Llacsahuanga Allcca,Kunhong Shen,Takashi Taniguchi,Kenji Watanabe,Sunil A. Bhave,Yong P. Chen,Yuan Ping & Tongcang Li
Nature Materials Published:15 August 2022
DOI:https://doi.org/10.1038/s41563-022-01329-8

Abstract

Electron spins in van der Waals materials are playing a crucial role in recent advances in condensed-matter physics and spintronics. However, nuclear spins in van der Waals materials remain an unexplored quantum resource. Here we report optical polarization and coherent control of nuclear spins in a van der Waals material at room temperature. We use negatively charged boron vacancy (V_B^ー) spin defects in hexagonal boron nitride to polarize nearby nitrogen nuclear spins. We observe the Rabi frequency of nuclear spins at the excited-state level anti-crossing of V_B^ー defects to be 350 times larger than that of an isolated nucleus, and demonstrate fast coherent control of nuclear spins. Further, we detect strong electron-mediated nuclear–nuclear spin coupling that is five orders of magnitude larger than the direct nuclear-spin dipolar coupling, enabling multi-qubit operations. Our work opens new avenues for the manipulation of nuclear spins in van der Waals materials for quantum information science and technology.