高压下金刚石NV色心能级变化及其对压力磁场的灵敏探测

Nitrogen-Vacancy (NV) center in diamond has found wide applications in quantum information and high sensitivity metrology of magnetic field, electric field and temperature at ambient pressure. However, the pressure-induced change in the energy level of NV center and its potential application in the metrology of pressure and magnetic field at high pressure remain to be investigated yet. The realization of metrology based on NV center at high pressure will provide a new approach for the study of matter subjected to high pressure with nanoscale resolution and high sensitivity. In this project, we propose to measure the optically detected magnetic resonance (ODMR) spectra under high pressure (0-60 GPa) in diamond anvil cell (DAC) which is expected to enable the following research. 1) The effect of pressure on the energy level structure and electron spin state of NV center, including pressure induced splitting between different spin states, coherence time of electron spin, optically spin polarization and fine structure of excited state. 2) Based on the pressure-induced energy level splitting, pressure sensor of NV center would be explored to access pressure gauge with high sensitivity promoted by dynamical decoupling techniques. The magnetic detection of NV center with nanoscale spatial resolution and high sensitivity has been demonstrated at ambient pressure. The high sensitivity metrology of magnetic field by NV center at high pressure will be explored by virtue of the shallow NV center residing close to the culet surface of diamond anvil. This proposal will help understand the energy level of NV center at high pressure comprehensively and provide a new high sensitivity metrology with nanoscale resolution for the research at extreme conditions.

金刚石NV色心已广泛应用于量子信息领域和常压下磁场、电场及温度的高灵敏度探测。然而，高压下NV色心的能级变化及其对压力、磁场的探测还有待研究。本项目拟采用金刚石对顶砧技术，实现NV色心高压(0-60 GPa)光探测磁共振谱的测量，并以此测量为主要手段进行以下研究：1）压力对NV色心能级结构和电子自旋态的影响，包括：不同自旋态之间的能级分裂、电子自旋的相干时间、光学自旋极化和激发态精细结构。2）基于压力导致的能级变化，探索NV色心对压力的灵敏探测。利用动力学解耦脉冲序列提高压力探测的灵敏度，实现高灵敏度压标。基于成熟的NV色心常压灵敏磁探测技术，利用金刚石压砧台面的浅层NV色心，探索高压下NV色心对磁场的灵敏探测。本项目的研究，有助于全面深入认识高压下NV色心的能级结构，为极端条件下的科学研究提供一种新的纳米尺度分辨率的灵敏探测手段。

金刚石中的NV色心(氮-空位缺陷)，由于其特殊的能级结构，具有光学极化和光学读取电子自旋态的性质，在量子信息领域被深入研究，近几年更是在高灵敏度探测方面得到广泛应用，例如，磁场探测，电场探测，力学振动探测，温度探测等。然而，目前NV色心对压力探测的研究相对较少，高压下NV色心的能级结构以及NV色心对压力的灵敏探测研究对于NV色心在高压科学的应用具有重要意义。在本项目的支持下，我们掌握了高压下金刚石对顶砧准备技术和样品装载技术，可成功的获得高压下金刚石NV色心样品；经过对样品的特殊处理以及对比研究，获得适合高压研究的高浓度NV色心含量的微米金刚石颗粒样品。实现了高压下金刚石中的NV-和NV0色心的荧光光谱测量，获得了不同压力下NV-和NV0色心的荧光光谱和零声子线（ZPL），确定了压力对NV色心的能级结构的影响。基于压力导致的能级变化，NV-和NV0色心的零声子线峰位随压力发生线性变化，标志着NV色心可应用于对压力的灵敏探测。另外，随着压力的增加，NV-和NV0色心的零声子线的峰位发生线性蓝移，带隙缩小，而且NV-色心的峰位移动速率是NV0色心的三倍，NV-色心的强度变化与NV0呈现不同趋势，说明压力对NV-和NV0色心的能级结构作用不同。