| The nonlinear electromagnetic response of the physical system driven by polychromatic fields can produce robust manipulation of the energy and observables of the target system,and is widely used in many leading-edge fields such as quantum precision measurement,quantum simulation and manipulation,and quantum magnetism.Among them,the radio-frequency multiphoton effect based on laserdetected multi-radio-frequency-driven alkali-metal magnetic resonance system is an important means for the development of magnetic induction tomography,radio-frequency atomic magnetic sensor,and quantum magnetic communication.In particular,the introduction of Floquet modulation technology,which can flexibly control the material structure,into the highly sensitive laser-detected magnetic resonance system has become a general platform for creating and characterizing novel physical phenomena and control of the state of matter.Moreover,the dynamical symmetry of the Floquet system can also be used to design the form of high-order harmonic generation and the driving pulse sequence of a specific magnetic resonance,and play an irreplaceable role in the fields of quantum precision measurement and quantum simulation.The research content of this dissertation is mainly based on the laser-detected cesium atomic magnetic resonance experimental platform to carry out a series of related theoretical and experimental research around the radio-frequency multi-photon effect and the high-dimensional symmetry theory of Floquet dynamics,including the development of radio-frequency two-photon atomic broadband magnetic sensing technology,investigation of the physical origin of spectral asymmetry induced by the radio-frequency multi-photon effect of magnetic resonance excited by two-color strong driving fields,the analysis of the relationship between the high-dimensional generalized parity and high-order polarization spectral symmetry of Floquet-driven large-spin atomic ensemble dynamics,and revealing the physical nature of the two-dimensional Floquet-driven large-spin atomic ensemble dynamics and highdimensional rotation symmetry-protected spectral selection rules.The specific research content of this dissertation is as follows:(1)Two-photon excitation is an important means to develop radio-frequency magnetic sensors.We discuss and experiment in detail the two-photon excitation schemes of Raman and cascade configurations to excite atomic magnetic resonance.Based on the laser detected cesium atomic magnetic resonance experimental platform,we investigate the effects of laser power,transmission spectra,atomic polarization distribution,and driving radio-frequency intensity and frequency on the performance of Raman and cascade magnetic resonance systems for measuring ac magnetic signals,and give the applicable parameter ranges of the systems.We develop broadband radio-frequency atomic magnetic resonance techniques based on radio-frequency cascade and Raman two-photon processes.This two-photon magnetic resonance is expected to be used in the development of broadband radio-frequency atomic magnetometer,multiphoton magnetic imaging,atomic radio-frequency magnetic communication and non-contact metal flaw detection and other technologies.(2)The multiphoton effect of strongly coupled systems is an important research content of quantum and atomic optics.Based on the laser-detected cesium atom magnetic resonance experimental platform,we carry out theoretical and experimental research on the multiphoton effect of two-color strong radio-frequency coupling magnetic resonance to break the spectral symmetry.To solve this problem,we use two transverse strong radio-frequency fields with close frequencies to drive the spin magnetic resonance of cesium atoms to construct a strongly coupled system.Our results show that weaker linear corrections of strong radio-frequency fields and nonlinear higher-order corrections induce the system to automatically generate Floquet modulation phenomena composed of multiharmonic components.In particular,the self-generated Floquet modulation leads to broadband continuous asymmetrical spectra in the system,and the even-order harmonic correction of the self-generated Floquet modulation is the direct cause of the spectral asymmetry.In addition,we also find that the Rabi frequency of the driving radio-frequency fields have approximately linear relationship with the spectral splitting interval and the maximum and submaximum intervals of the continuous spectra.These research results are expected to be used in the development of multiphoton magnetic sensing technology,spectral shaping technology,and quantum simulation and manipulation technology of strongly coupled systems.(3)Dynamical symmetry is an important tool to predict and reveal the electromagnetic response of Floquet systems.Based on the Floquet-modulated large-spin magnetic resonance platform of cesium atoms,we reveal the physical origin of the dynamical high-dimensional generalized parity-protected high-order polarization spectral symmetry.We use the longitudinal two-color Floquet field to drive the ground state large-spin magnetic resonance of cesium atoms to constructa system with dynamical high-dimensional generalized parity symmetry.By analyzing the system’s multiphoton process,angular momentum probability surface,and Floquet sideband transition weights and other information,the relationship between atomic tensor polarization distribution,second-order tensor polarization spectrum symmetry breaking and dynamical high-dimensional generalized parity is revealed from multiple perspectives.It is found that dynamical high-dimensional generalized parity symmetry is a sufficient condition for maintaining spectral symmetry.These results not only enrich the theory and experiment of high-dimensional generalized parity of Floquet large-spin ensemble dynamical systems,but also promote the design of highly sensitive vector atom magnetometers based on high-order polarization moments.(4)We have further carried out the theory and experiment of dynamical high-dimensional rotation symmetry and spectral selection rules of large-spin magnetic resonance systems modulated by twodimensional Floquet fields.We combine Floquet-driven technology and resonance-driven technology to establish a magnetic resonance system with dynamical high-dimensional rotation symmetry,and develop an experimental technique for direct observation of spectral sideband selectivity in multiple directions to verify dynamical high-dimensional rotation symmetry and spectral selection rules.Our results show that the selection rules for the spectra observed along and perpendicular to the reflector are opposite.At the same time,it is also verified that the polarization direction of the odd harmonic generated by the system is perpendicular to the reflection plane,and the polarization of the even harmonic generated is allowed within the reflection plane.These results not only further deepen the theory and experiment of high-dimensional rotation symmetry in large-spin dynamics,but also the experimental technology for preparing and detecting symmetry developed by us is expected to be used in the fields of Floquet quantum manipulation and quantum simulation. |
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