Spin-coherence characterization of boron vacancy defects in hexagonal boron nitride with broadband microwave pulses

Yuki Nakamura; Takuya Iwasaki; Shu Nakaharai; Shinichi Ogawa; Yukinori Morita; Kenji Watanabe; Takashi Taniguchi; Kento Sasaki; Kensuke Kobayashi

arXiv · 2604.27843

Spin-coherence characterization of boron vacancy defects in hexagonal boron nitride with broadband microwave pulses

Yuki Nakamura·Takuya Iwasaki·Shu Nakaharai·Shinichi Ogawa·Yukinori Morita·Kenji Watanabe·Takashi Taniguchi·Kento Sasaki·Kensuke Kobayashi

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Abstract

Negatively charged boron vacancy (VB-) defects in hexagonal boron nitride (hBN) are promising for nanoscale-proximity quantum sensing. To evaluate their performance, it is important to characterize the spin coherence times T2* and T2. In this study, we realized sub-GHz Rabi oscillations of VB- using an isotopically enriched hBN thin film directly stamped onto a narrow gold wire. Using these strong microwave pulses, we performed Ramsey interference and Hahn echo measurements. The Ramsey interference signal showed Gaussian-like decay, yielding T2* = 13.8 ns. The Hahn echo measurement gave T2 = 108.7 ns and a stretch factor of {\alpha}= 1.25. These results experimentally clarify the spin coherence properties of VB- and provide an effective method for evaluating the coherence of spin defects in van der Waals thin films with broad resonance linewidths.

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Yuki Nakamura, Takuya Iwasaki, Shu Nakaharai, Shinichi Ogawa, Yukinori Morita, Kenji Watanabe, Takashi Taniguchi, Kento Sasaki, Kensuke Kobayashi. 2026-04-30. Spin-coherence characterization of boron vacancy defects in hexagonal boron nitride with broadband microwave pulses. https://arxiv.org/abs/2604.27843

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