Key Technology Studies Of Quantum Measurement Based On Ensembles Of NV Centers In Diamond

Magnetic sensing technology of Nitrogen-Vacancy(NV)center in diamond has made great progress because of the development of physical research and quantum control technologies.In addition,the technology of magnetic detection using diamond NV color center with small size,high sensitivity and stable chemical properties is increasingly demanding.Ensembles of NV centers has become a hot research topic in quantum magnetic sensing due to its advantages of high photon counting rate,simple detection method,and long relaxation time.Because the interactions between the NV center in diamond and the surrounding environment will result in the occurrence of de-coherence,and those phenomenon can lead to a decrease in the sensitivity of the magnetic field detection.The use of precise quantum control technology for control to increase the magnetic field detection sensitivity has become the hot topic of quantum metrology.So this article mainly contains following research:Firstly,we introduced the energy level and crystal structure of NV center in diamond and the model of de-coherence time quantum control,theoretically.Then,The Hamiltonian of NV centers in diamond under different conditions is presented.In addition,we studied the basic principles of quantum manipulation for ensemble NV centers.The study of these theories lays the foundation for subsequent quantum measurement.Next,in order to achieve accurate quantum measurement,we developed a home-built random pulse sequence generation program based on LabVIEW,which can control multiple high-precision pulses accurately and achieve to operate various instruments synchronously.Besides,we developed a set of dedicated data acquisition program for quantum manipulation,which can be used for pulse trigger data acquisition.Finally,the weak magnetic field detection system based on NV color center wasoptimized.We obtained the relationship between the sensitivity of the magnetic field detection and the laser and microwave power,which can be used for finding the optimal parameters of the laser and microwave power to realize maximum sensitivity.Further,we performed Rabi oscillation measurements.The research of Rabi oscillation period measurements laid the foundation for dynamic decoupling and de-phasing time detection.Next,the transverse relaxation time and the dephasing time were measured.This study preliminarily realized the controlling of the NV color center in diamond through microwaves and laser light.Further,we performed some of the coherent properties.These studies lay the foundation for realizing the dynamic decoupling to extend the de-coherence time.