Analysis of high-harmonic generation in terms of complex Floquet spectral analysis
Analysis of high-harmonic generation in terms of complex Floquet spectral analysis
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用复 Floquet 谱分析分析高次谐波的产生
DOI：
10.1109/piers-fall.2017.8293356
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Petrosky
中科院分区：
文献类型：
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作者：
Hidemasa Yamane;Satoshi Tanaka;M. Domina;R. Passante;T. Petrosky
强激光光源的最新发展为光学科学开辟了一个新的领域。强相干光束与物质强烈相互作用，导致粒子的相干运动，形成强烈修饰的激发粒子。从这个被修饰的激发粒子的光子发射是一个强非线性过程，导致高次谐波产生（HHG），其中微扰分析被打破。本文在扩展的Floquet-Hilbert空间中，利用复谱分析方法研究了强缀饰激发态原子的相干光子辐射。我们用Feshbach-Brilloiun-Wigner投影方法得到了总哈密顿量的本征态。在这个扩展空间中，由辐射场和原子系统组成的总哈密顿量的本征态具有复本征值，其虚部代表衰变率。系统的时间演化由复本征矢展开表示，从而充分考虑了光子与原子之间的关联动力学。高次谐波是由周期性外场作用下产生的多重Floquet态的共振奇异性引起的不可逆自发光子辐射。我们发现，不同Floquet态的发射光子之间的干涉导致与激发原子的衰变过程相关的空间脉冲发射。
Recent developments on intense laser sources is opening a new field of optical sciences. An intense coherent light beam strongly interacting with the matter causes a coherent motion of a particle, forming a strongly dressed excited particle. A photon emission from this dressed excited particle is a strong nonlinear process causing high-harmonic generation (HHG), where the perturbation analysis is broken down. In this work, we study a coherent photon emission from a strongly dressed excited atom in terms of complex spectral analysis in the extended Floquet-Hilbert-space. We have obtained the eigenstates of the total Hamiltonian with use of Feshbach-Brilloiun-Wigner projection method. In this extended space, the eigenstates of the total Hamiltonian consisting of the radiation field and the atom system have complex eigenvalues whose imaginary part represents the decay rate. Time evolution of the system is represented by the complex eigenvector expansion so that the correlation dynamics between the photon and the atom is fully taken into account. The HHG is interpreted as the irreversible spontaneous photon emission due to the resonance singularity in terms of the multiple Floquet states that are generated by periodic external field. We have found that the interference between the emitted photons over the different Floquet states causes spatial pulse emission correlated with the decay process of the excited atom.