Speaker
Description
Spin defects in solid-state systems are powerful platforms for quantum sensing and quantum information storage due to their long coherence times and compatibility with scalable architectures. In this work, we present scanning probe microscopy utilizing the nitrogen vacancy (NV) center in diamond to locally detect and image spin-based quantum sensors at the nanoscale. Specifically, we study the negatively charged boron vacancy (V$_\text{B}^-$) center in hexagonal boron nitride (hBN), itself a promising two-dimensional quantum sensing platform. Rather than relying on the V$_\text{B}^-$ center optical properties, we detect its spin transitions through their impact on the longitudinal spin relaxation time ($T_1$) of a nearby NV. Relying on cross-relaxation between NV and V$_\text{B}^-$ spins, this indirect detection scheme circumvents the need for optical excitation or fluorescence collection from the hBN itself. When the NV and V$_\text{B}^-$ spin transitions become resonant, the $T_1$ of the NV shortens significantly, allowing selective sensing of the local V$_\text{B}^-$ density. We use this mechanism to spatially map the distribution of V$_\text{B}^-$ centers with nanoscale resolution, well beyond the diffraction limit of optical imaging. In isotopically purified h$^{10}$B$^{15}$N, we further resolve hyperfine interactions, highlighting the sensitivity of the technique to fine spectral features. Our results showcase a hybrid sensing architecture in which 3D NV sensors serve as readout channels for 2D spin systems, opening new possibilities for characterization of optically inactive spin defects in layered materials.
| Topical Area | Hard matter: quantum, electronic, semiconducting materials |
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