High Signal-to-noise Ratio Magnetometer Based On NV Color-centered Light Detection Of Magnetic Resonance

The nitrogen-vacancy（NV）color center in diamond is a highly sensitive and high spatial resolution quantum sensor that can be used to measure physical quantities such as magnetic field,electric field,and temperature.In addition,the NV color center is also an excellent quantum bit system for initialization,manipulation and readout of spin states at room temperature.In this paper,a high signal-to-noise ratio magnetometer and fluorescence spectrum acquisition and conversion device based on optically detected magnetic resonance（ODMR）spectroscopy is designed based on the response mechanism of NV color center to magnetic field,and the subsequent quantum tuning to enhance the sensitivity of NV color center magnetometer and the remaining angles for magnetometer The experimental design and demonstration of the integration and sensitivity enhancement are carried out as follows.First,the diamond type and the atomic structure of the NV color center are introduced,and the sensing theory of the diamond NV color center based ODMR magnetometer based on the principle of energy level jump of the NV color center is also introduced.In order to further improve the signal-to-noise ratio and the ease of use of the system,a high signal-to-noise ratio ODMR spectroscopy and fluorescence spectroscopy conversion integrated system is designed,and the final signal-to-noise ratio is improved by 252.3 times,and the magnetic measurement sensitivity reaches 0.51 n T/Hz^1/2.Second,the experimental design and study were conducted to improve the magnetic measurement sensitivity of NV color-centered magnetometer by both quantum modulation and magnetic flux aggregation.By adding Pulse Blaster board and acousto-optical modulator to the integrated system,the pulse timing control of microwave,laser and collector is realized to improve the magnetic measurement sensitivity of the system;a new flux aggregator is also designed to improve the spatial magnetic field sensitivity of the magnetometer to further improve the magnetic measurement sensitivity.Third,new directions are provided to further improve the sensitivity and integration of the diamond NV color center magnetometer.Firstly,a system that can control and generate a uniform magnetic field by using permanent magnets and Helmholtz coils together is built to solve the constraint that it is difficult to generate a stable magnetic field in the ground state energy level anti-crossing region Bz=102.4 m T,and the experimental feasibility is proved by the collected data.A field-programmable gate array（FPGA）and a lock-in amplifier were also used to build an experimental system for short-circuit conversion,which opens up new research directions for further improvement of magnetometer sensitivity.