Magnetic Nanoscopy with Diamond NV Centers

提出了一种利用金刚石中氮空位色心薄层并结合亚光波长探测技术实现纳米级磁场成像的新方法。到目前为止，具有单个NV中心的磁场感测已经显示出5 nT/Hz 1/2的灵敏度。这已经足以探测到50 nm距离处的单个电子自旋或5 nm处的单个核自旋。同时，NV中心的尺寸估计为0.3 nm。没有其他磁传感器在这种距离范围内具有这种灵敏度。纳米尺度的磁场图像已经与NV中心使用扫描探针技术，和微尺度的全帧成像与合奏已被证明。亚波长受激发射耗尽显微镜也已完成使用单NV中心，并实现了优于10 nm的分辨率，即使与低强度甜甜圈光束。该方法是使用合奏，以消除需要控制纳米精度的扫描探针附近的目标，同时使用耗尽显微镜，以保持空间分辨率。然而，要实现这一潜力，首先必须更好地了解NV系综的物理特性，特别是它们的磁灵敏度如何取决于NV浓度以及与受激发射耗尽（STED）和基态耗尽显微镜（GSD）中使用的激光的相互作用。该项目将建立在伯克利和得克萨斯州A M集团现有的综合专业知识和基础设施的基础上。 该项目的顶点将是一个生物相关系统的磁性纳米显微镜--Tritonia diomedea中直径为100纳米的磁性链--一种以其在地球磁场中导航的能力而闻名的海蛞蝓。拟议的研究将导致优化的NV-金刚石系综空间分辨系综磁力，阐明NV中心的基本物理学（包括确定磁共振参数的温度依赖性等），理解STED/GSD泵浦光束对灵敏度的影响，并基于此知识开发优化的磁力测量方法。预期的纳米级传感器将具有足够的灵敏度，可以看到材料中的纳米级磁畴。广泛的影响将是提供一种替代磁共振力显微镜没有移动部件。由于主机的极端化学稳定性和远程光学检测协议，NV中心也可以用于微流体“芯片实验室”系统，允许使用微量分析物进行化学分析和成像。这在工业、安全和医学中是一个重要的应用，因为它可以快速和普遍地识别危险物质。一个关键的应用领域是生物系统的磁成像，这将通过对Tritonia diomedea中磁链的测量来证明。钻石色心的研究具有广泛的教育影响，因为NV中心的简单几何形状是理解量子力学和固态物理学更广泛概念的方便教学工具。NV合奏可以演示磁感应原理的学生只使用激光笔和磁铁。 让K-12学生进行动手磁感应，结合钻石的社会神秘主义，也可以作为一种新的招聘工具，为妇女等代表性不足的群体。本科生的参与，特别是通过伯克利大学生研究学徒计划和TAMU的实验光学课程，计划。

A novel approach to nanoscale magnetic-field imaging using a thin layer of nitrogen-vacancy (NV) color centers in diamond and combining this with sub-optical-wavelength probing techniques is proposed. Magnetic-field sensing with single NV centers so far has shown a sensitivity of 5 nT/Hz1/2. Already this is sufficient to detect a single electron spin at 50 nm distances or a single nuclear spin at 5 nm. At the same time, the NV center is estimated at 0.3 nm in size. No other magnetic sensor has this sensitivity on this distance scale. Nanoscale magnetic field images have been made with NV centers using scanning-probe techniques, and microscale full-frame imaging with ensembles has been demonstrated. Sub-wavelength stimulated emission depletion microscopy has also been done using single NV centers and achieved better than 10 nm resolution even with low-intensity donut beams. The approach is to use ensembles to eliminate the need to control a scanning probe with nanometer precision near the object of interest while using depletion microscopy to maintain the spatial resolution. However, to realize this potential one must first better understand the physics of NV ensembles, especially how their magnetic sensitivity depends on NV concentration and interactions with the lasers used in the stimulated-emission-depletion (STED) and ground-state-depletion microscopy (GSD). The project will build on the combined expertise and infrastructure available to the Berkeley and Texas A&M groups. The apex of the project will be magnetic nanoscopy of a biologically relevant system---100 nm diameter magnetic chains in Tritonia diomedea---a sea slug known for its ability to navigate in the Earth's magnetic field.Intellectual merit: The proposed studies will lead to optimization of the NV-diamond ensembles for spatially-resolved ensemble magnetometry, elucidation of the fundamental physics of the NV-centers (including determination of temperature dependence of the magnetic-resonance parameters, etc.), understanding of the effect of the STED/GSD pump beam on sensitivity, and development of optimized magnetometry methodology based on this knowledge. The anticipated nanoscale sensor will have enough sensitivity to see nanoscale magnetic domains in materials. Broad impact will be to provide an alternative to magnetic resonance force microscopy with no moving parts. Due to extreme chemical stability of the host and the remote optical detection protocol, NV centers can also be used in microfluidic ``lab-on-a-chip'' systems, allowing chemical analysis and imaging with minute quantities of analytes. This is an important application in industry, security, and medicine, as it allows rapid and universal identification of dangerous substances. A key area of application is magnetic imaging of biological systems which will be demonstrated by measurements on magnetic chains in Tritonia diomedea. The study of color centers in diamond has broad educational impact, as the simple geometry of the NV center is a convenient teaching tool for understanding the broader concepts of quantum mechanics and solid-state physics. NV ensembles can demonstrate the principles of magnetic sensing to students using only a laser pointer and a magnet. Letting K-12 students perform hands-on magnetic sensing, combined with the social mystic of diamonds can also be used as a novel recruiting tool for underrepresented groups such as women. Involvement of undergraduates, specifically through the Berkeley undergraduate-research-apprenticeship program and TAMU's experimental optics course, is planned.