Nanoscale Magnetic Resonance Imaging Study Based On Nitrogen-vacancy Center

As one of the basic physical quantities,the precise measurement of magnetism has promoted the solid development of magnetism-related fields.Various detection tech-nologies are working to improve spatial resolution and sensitivity,from Hall detectors,spin magnetic resonance to superconducting quantum interferometers(SQUID).In re-cent years,thanks to the development of quantum technology,the diamond nitrogen-vacancy(NV)center system,as the application of quantum information,can be used as a quantum sensor for magnetic precision measurement.The diamond nitrogen-vacancy center is a solid-state spin system whcih is easy to initialize,manipulate,and read out.It not only makes its debut in the field of quantum computing,but also shows great appli-cation prospects in the field of quantum precision measurement.Based on this system,a series of breakthrough advances in magnetic resonance spectroscopy and imaging have been achieved experimentally.The spatial resolution has been improved from sub-millimeters to sub-nanometers,the number of molecules has gone from billions to a single,and even single-proton signal intensity has been reached.Magnetic resonance detection.In addition,it has led to the upsurge of applied research in the fields of physics,chemistry,and biology.This thesis selects the topic under this research background,de-velops the nano-magnetic imaging technology using the nitrogen-vacancy center as the magnetic signal quantum sensor,and applies it to the cross-research in the field of life science,and the in situ ferritin detection of cells.The research background of this doctoral dissertation first briefly introduces var-ious systems that can be used for quantum precision measurement;then it focuses on the basic physicochemical properties of the diamond NV center and the basic principles that can be used for magnetic signal detection;at the end,it gives an overview Research progress in nano/single molecule magnetic resonance internationally.The second chapter of the thesis is the main part of this article,which systemati-cally introduces our spectrometer and technology,experimental schemes and results.In order to image cells,a method of scanning a cell sample on the surface of a diamond probe is used.We first built an atomic force microscope(AFM)-light detection mag-netic resonance(ODMR)joint spectrometer,which can detect the NV center.Quantum manipulation can also be used to scan samples in nanometer steps to achieve imag-ing;then the imaging principle is explained.Since the detection object is the in-situ paramagnetic ferritin,when the distance is close enough,it will lead to shortened NV coherence time and relaxation time.Then,combined with the scanning of the atomic force microscope,an image of the distribution of ferritin in the cells can be obtained.Finally,the main experimental results and analysis are introduced,and the in situ ferritin imaging at a resolution of ten nanometers is realized.The third chapter of the thesis shows a new method that can increase and decrease the decoherence caused by the environment by combining Toler decomposition and dy-namic decoupling pulses.This solution takes advantage of the inherent decoherence effect in the environment,and includes the universality of digital quantum simulation and the advantages of high efficiency of analog quantum simulation.This hybrid sim-ulation method performs numerical simulations on the two-and three-level systems of NV centers.The research results here show that this scheme also contains potential in experiment.In this way,it paves the way for NV centers and other similar systems to simulate actual physical systems.It is easy to accurately simulate the equivalent envi-ronmental noise like qubits,allowing the original annoying decoherence to play roles in simulation.It can be seen from the above experimental introduction that the coherence time and relaxation time of the single spin of the NV center are both important for precise measurement and quantum calculation.These two indicators are mainly determined by the magnetic noise in diamond.Our related theory Both the environmental noise of the NV center and the experimental work have been studied.Finally,the control of single spin of NV center is introduced,and the main work of this paper is briefly summarized and prospected.