Spin Control Method And Wide-field Imaging Of Diamond NV Centers Based On Microwave Pulse Shaping Technology

In recent years,the quantum precision magnetic measurement technology based on nitrogen-vacancy（NV）color centers in synthetic diamond has developed rapidly and demonstrated enormous potential to meet the testing needs of industrial magnetic measurement fields due to its stable physical properties at room temperature,ability to interact with multiple physical fields,no need for complex testing environments,indirect readout of spin states using optics,and lifetime testing without calibration.In order to further meet the industrial magnetic testing needs,the ensemble NV center sensing system has become a leading topic in quantum precision magnetic measurement research due to its high sensitivity,excellent fluorescence rapid readout mechanism,and high dynamic testing range.However,for the diamond NV color center environment,due to the inherent property of wide frequency band excitation for typical rectangular pulses,it is inevitable to cause spin coupling interactions between the non-uniformly distributed dark spin impurities in the diamond lattice and the target NV color center when performing optical detection magnetic resonance（ODMR）.It is this interaction that results in a sideband excitation spectrum that coincides with the target NV color center on the ODMR spectrum and a shift in the NV color center spin resonance frequency,leading to a significant gap in the sensitivity,sampling rate（temporal resolution）and power measurement dynamic range of the diamond NV color center spin excitation magnetic measurement technology based on ODMR from the Heisenberg physical testing limits.Based on the above research background,this paper utilizes the band-selective spin excitation characteristics of shaping pulses to carry out the research on microwave shaping pulse spin control method and wide-field imaging based on diamond NV color centers.The main work is as follows:（1）By constructing the spin ground state Hamiltonian and analyzing the diamond NV spin ODMR magneticmeasurement mechanism from the internal and external environment effects on the diamond NV spin system,this paper designs and builds an experimental system,prepares and characterizes the magnetic sensing element of diamond NV color centers,and performs experimental verification of relevant basic magnetic measurements according to the basic properties of the diamond NV spin system and magnetic measurement principles.（2）Aiming at the difficulty in improving the sensitivity and signal-to-noise ratio of diamond NV centers magnetic field measurement,a Gaussian shaped pulse ODMR spin control method is proposed.This method effectively suppresses the excitation of sidebands caused by P1 center spin impurities and ¹³C nuclear spin,and solves the problem of reduced contrast and linewidth distortion of the target ODMR spectrum when increasing the NV concentration and the microwave power.After qualitative experimental verification,the corresponding optimization sensitivity and signal-to-noise ratio indicators are obtained by optimizing the testing parameters such as laser power,microwave power,integration time,and polarization time.（3）In order to solve the problem that the interaction between spin impurities and target NV center,which affects the sensitivity,temporal resolution and microwave power dynamic range of diamond NV color center microwave wide-field imaging experiments,a sin shaped pulse Rabi oscillation spin controlled diamond NV color center microwave wide-field imaging method is proposed.This method can effectively suppress the spin resonance frequency shift caused by the interaction of dark spin impurities and microwave,and improve the microwave power dynamic range of microwave wide-field imaging with sufficient sensitivity.Subsequently,aiming at the imaging distortion caused by non-uniform excitation environments above 1mm²wide field excitation conditions,a microwave wide field imaging compensation technique based on diamond NV color center laser excitation factor balance is proposed in combination with the sin shaped pulse Rabi oscillation spin control method,this method can effectively eliminate the non-uniform excitation noise caused by non-uniform excitation luminescence,non-uniform NV color center distribution,and non-uniform spin impurity distribution.The imaging experimental results show that this method can restore the microwave interference ripple phenomenon which is generated by high-power microwave on the antenna surface.