Department of Nuclear Science and Engineering and Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Nat Commun. 2014;5:3141. doi: 10.1038/ncomms4141.
Quantum probes can measure time-varying fields with high sensitivity and spatial resolution, enabling the study of biological, material and physical phenomena at the nanometre scale. In particular, nitrogen-vacancy centres in diamond have recently emerged as promising sensors of magnetic and electric fields. Although coherent control techniques have measured the amplitude of constant or oscillating fields, these techniques are not suitable for measuring time-varying fields with unknown dynamics. Here we introduce a coherent acquisition method to accurately reconstruct the temporal profile of time-varying fields using Walsh sequences. These decoupling sequences act as digital filters that efficiently extract spectral coefficients while suppressing decoherence, thus providing improved sensitivity over existing strategies. We experimentally reconstruct the magnetic field radiated by a physical model of a neuron using a single electronic spin in diamond and discuss practical applications. These results will be useful to implement time-resolved magnetic sensing with quantum probes at the nanometre scale.
量子探针可以高灵敏度和空间分辨率地测量时变场，从而能够在纳米尺度上研究生物、材料和物理现象。特别是，钻石中的氮空位中心最近已成为磁场和电场的有前途的传感器。尽管相干控制技术已经测量了恒定或振荡场的幅度，但这些技术不适用于测量具有未知动态的时变场。在这里，我们引入了一种相干采集方法，使用 Walsh 序列来精确重建时变场的时间轮廓。这些解耦序列充当数字滤波器，在抑制退相干的同时有效地提取频谱系数，从而提供比现有策略更高的灵敏度。我们使用钻石中的单个电子自旋实验重建了神经元物理模型辐射的磁场，并讨论了实际应用。这些结果将有助于在纳米尺度上使用量子探针实现时间分辨磁传感。
