Polarization control of above-threshold ionization spectrum in elliptically polarized two-color laser fields

We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the photoelectron.Particularly for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency field.With the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is high.Moreover,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical prediction.Our investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.

血浆T-tau、Aβ-42与维持性血液透析患者轻度认知功能障碍的相关性研究

目的探讨血浆T-tau、Aβ-42蛋白浓度与维持性血液透析患者认知功能障碍的相关性。方法采用酶联免疫吸附法检测轻度认知功能障碍(MCI)组、认知功能正常组(对照组)血浆T-tau、Aβ-42蛋白浓度。分析两组血浆T-tau、Aβ-42蛋白浓度差异,及其与其他临床指标的相关性。结果 MCI组较对照组血浆T-tau蛋白浓度升高(P <0.05);两组Aβ-42蛋白浓度比较,差异无统计学意义(P>0.05);两组血浆T-tau蛋白浓度与尿素下降率、每2周透析时间呈负相关(r=-0.249,P=0.020);T-tau≥980.96 pg/ml为MCI的危险因素[O^R=1.521(95%CI:1.168,1.981),P=0.002]。结论维持性血液透析MCI患者血浆T-tau蛋白浓度较认知功能正常者升高,降低血浆T-tau蛋白浓度可能是预防维持性血液透析患者MCI的有效手段。

Influence of intraband motion on the interband excitation and high harmonic generation

Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation(HHG) in strong-field interaction with atoms.However, the periodic array of atoms in semiconductor structure makes three steps become interatomic coherent process which leads to complicated carrier dynamics and two sources of high harmonic emission: interband polarization and intraband current.The difference of features of high harmonic generation between semiconductors and atoms is strongly linked to the unique presence of intraband motion which manifests itself a nontrivial role in intertwined two dynamics.Here, we review recent experimental and theoretical advances of understanding coupled interband and intraband mechanisms of HHG in semiconductors.Particularly we focus on the influence of intraband motion on the interband excitation, and on the subsequent HHG emission and attosecond pulse generation.

Review on typical applications and computational optimizations based on semiclassical methods in strong-field physics

The semiclassical method based on Feynman’s path-integral is in favor of uncovering the quantum tunneling effect,the classical trajectory description of the electron, and the quantum phase information, which can present an intuitive and transparent physical image of electron’s propagation in comparison with the ab initio time-dependent Schr ¨odinger equation.In this review, we introduce the basic theoretical concepts and development of several semiclassical methods as well as some of their applications in strong-field physics. Special emphasis is placed on extracting time delay on attosecond scale by the combination of the semiclassical method with phase of phase method. Hundreds of millions of trajectories are generally adopted to obtain a relatively high-resolution photoelectron spectrum, which would take a large amount of time. Here we also introduce several optimization approaches of the semiclassical method to overcome the time-consuming problem of violence calculation.