基于磁集聚效应的系综NV色心磁检测增强

Enhancement of magnetic detection by ensemble NV color center based on magnetic flux concentration effect

高灵敏色心量子自旋磁检测是弱磁、极弱磁检测及成像应用的关键.本文通过搭建结合磁力线集聚结构(MFC)的系综金刚石氮空位(NV)色心的宽视场磁分布成像系统,对系综金刚石NV色心磁检测增强进行了系统研究.首先基于磁力线集聚效应仿真设计并制造了成对的T型薄片状MFC结构,利用连续波光探测磁共振(ODMR)宽视场磁成像技术对MFC的磁增强效果进行验证.实验测试的MFC间距的最小值为1.0 mm,此时磁增强倍数约为10.35,通过进一步对比不同磁场强度以及不同间距条件下的MFC磁增强效果,验证了MFC磁增强效果的有效性,系统磁检测灵敏度由1.10 nT/Hz^(1/2)提升至0.30 nT/Hz^(1/2).通过进一步对比仿真与测量获得的磁增强倍数与间隙宽度的关系,可对实验系统的磁增强及灵敏度进行有效估计.在MFC间距为0.5 mm时,对应的磁增强倍数可提升至约18.21,磁灵敏度则可达0.25 nT/Hz^(1/2).以上结果表明基于磁集聚效应可以实现系综金刚石氮空位色心磁检测灵敏度的有效提升,为精密量子测量技术在弱磁、极弱磁检测应用方面提供了参考.

The high-sensitivity magnetic sensor is the key to the weak magnetic and extremely weak magnetic detection imaging.In this paper,based on ensemble nitrogen-vacancy(NV)color center in diamond,a wide-field magnetic field distribution imaging system combined with the magnetic flux concentrator(MFC)is built for enhancing the magnetic detection.The paired T-shape chip MFC structures are designed and prepared based on the simulation of magnetic flux concentration effect,and the enhancement of magnetic field of MFC is verified by continuous wave optical detection magnetic resonance(CW-ODMR)imaging technology.When the gap width between the MFCs is 1.0 mm,the magnetic enhancement factor is about 10.35.To verify the effectiveness of the magnetic enhancement effect of the MFC,The magnetic enhancement effects are also measured under different magnetic field strengths and different gap widths.The magnetic sensitivity of the system increases from 1.10 nT/Hz^(1/2) to 0.30 nT/Hz^(1/2).By comparing the simulations with the measurements,the relationship between the measured magnetic enhancement multiple and the gap width can be obtained,and the better magnetic enhancement capability and sensitivity of the experimental system are also estimated.When the MFC’s gap width is 0.5 mm,the corresponding magnetic enhancement factor is increased to 18.21,and the corresponding magnetic sensitivity is 0.25 nT/Hz^(1/2).These results show that the magnetic detection sensitivity of the ensemble NV in diamond can be effectively improved based on magnetic flux concentration effect,which provides a reference for the applications of precision quantum measurement technology in weak magnetic and extremely weak magnetic detection.