Spin-Exchange Relaxation-Free Atomic Magnetometer And Its Application On Zero-and Ultralow-Field NMR

The spin-exchange relaxation-free(SERF)magnetometer has been the most sensitive magnetometer so far,whose demonstrated sensitivity has exceeded 1fT/(?).With the advantages of absence of superconducting magnets and cryogenics,SERF atomic magnetometers have found a wide range of applica-tions,and much effort has been devoted to detecting zero-and ultralow-field(ZULF)NMR.As an indispensable part of NMR,ZULF NMR utilizes encod-ing techniques which do not rely on chemical shifts,and it has advantages of extremely homogeneous fields(both spatially and temporally)for narrow lines.In this dissertation,we investigate the applicability of ZULF NMR based on the SERF magnetometer.There are two main aspects included:demonstrating a ZULF-NMR spectrometer based on the SERF magnetometer,and investigating the dynamics of nuclear spins under local spin-spin coupling interactions.This thesis is organized as followings:1.In chapter 1,the background and history of ZULF NMR are briefly intro-duced.2.In chapter 2,the basic process of atomic magnetometer is theoretically illustrated.3.In chapter 3,the scheme of SERF magnetometer is proposed,and the phys-ical system is carefully studied.According to our measurement,the opti-cally pumped atomic magnetic works in the SERF regime,and we acquire the sensitivity about 18 fT/(?),which is adequate for NMR detection.4.In chapter 4,the manipulation of ZULF spectrometer is presented’from the hardware and software.Based on the Python programming language,we realize the instrument control and data processing and develop the graphical user interface.In addition,we present experimentally the spin-spin spectra under ZULF environments to illustrate the unique feature of ZULF NMR.5.In chapter 5,based on the ZULF magnetometer,we implement the opti-mal control using zero-field nuclear magnetic resonance.The theoretical solution is based on the Pontryagin maximum principle and a symmetry reduction technique.This reveals experimentally an average fidelity 99%and a 70-80%decrease in the experiment duration compared with com-bined pulses.6.In chapter 6,we present a proposal for gas-phase NMR based on spin-exchange optical pumping(SEOP)and atomic magnetometry.This work extends SEOP to the alkali-metal-heteronuclear-gas system theoretically,and takes the 13C-labeled methane as an illustrating example for the cal-culations.According to our analysis,the magnetization generated by the gaseous molecules can be detected with a SERF magnetometer,which thus provides a promising approach in achieving high-sensitivity gas-phase NMR.7.Finally,a summary of this paper,and prospects.