Department of Electrical Engineering and Computer Science, MIT , Cambridge, Massachusetts 02139, United States.
Nano Lett. 2014 Jan 8;14(1):32-6. doi: 10.1021/nl402799u. Epub 2013 Nov 15.
The combination of long spin coherence time and nanoscale size has made nitrogen vacancy (NV) centers in nanodiamonds the subject of much interest for quantum information and sensing applications. However, currently available high-pressure high-temperature (HPHT) nanodiamonds have a high concentration of paramagnetic impurities that limit their spin coherence time to the order of microseconds, less than 1% of that observed in bulk diamond. In this work, we use a porous metal mask and a reactive ion etching process to fabricate nanocrystals from high-purity chemical vapor deposition (CVD) diamond. We show that NV centers in these CVD nanodiamonds exhibit record-long spin coherence times in excess of 200 μs, enabling magnetic field sensitivities of 290 nT Hz(-1/2) with the spatial resolution characteristic of a 50 nm diameter probe.
氮空位（NV）中心在纳米金刚石中具有长自旋相干时间和纳米级尺寸，这使其成为量子信息和传感应用的研究热点。然而，目前可用的高温高压（HPHT）纳米金刚石具有高浓度的顺磁杂质，这将其自旋相干时间限制在微秒量级，不到体金刚石中观察到的自旋相干时间的 1%。在这项工作中，我们使用多孔金属掩模和反应离子刻蚀工艺从高纯度化学气相沉积（CVD）金刚石中制备纳米晶体。我们表明，这些 CVD 纳米金刚石中的 NV 中心表现出超过 200 μs 的超长自旋相干时间，从而实现了超过 290 nT Hz(-1/2)的磁场灵敏度，并且具有 50nm 直径探针的空间分辨率特征。
