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Dynamics of strong-field double ionization of H2 in co-rotating two-color circularly polarized laser fields

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Communications in Theoretical Physics 2020年第5期72卷 85-91页

作者： Dan Wu Fu-Ming Guo jun Wang Ji-Gen Chen yu-jun yang Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Department of Materials Engineering Taizhou UniversityTaizhou 318000China

Double ionization of H2 in a co-rotating two-color circularly polarized(TCCP)laser field is theoretically *** changing the ratio of electric field peak amplitudes of the TCCP laser pulses,the double ionization probability as a function of the laser intensity shows a clear knee structure,which is suppressed significantly in the case of the *** to the large spatial range of the electronic initial distribution,with the analysis of classical trajectories of ionized electrons,it is found that the ionization of the electron in the farther distance increases the probability of ***,the yield of nonsequential double ionization created by the recollision can be enhanced by controlling the amplitude ratio of the TCCP laser field.

关键词： circularly polarized laser field knee structure H2

Resonance-enhanced two-photon ionization of hydrogen atom in intense laser field investigated by Bohmian-mechanics

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Chinese Physics B 2020年第9期29卷 288-294页

作者： yang Song Shu Han yu-jun yang Fu-Ming Guo Su-yu Li College of Science Northeast Electric Power UniversityJilin 132012China Archives Northeast Electric Power UniversityJilin 132012China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

Resonance enhanced two-photon ionization process of hydrogen atom via the resonant laser pulse is studied by Bohmian mechanics (BM) method. By analyzing the trajectories and energies of Bohmian particles (BPs), we find that under the action of high frequency and low intensity multi-circle resonant laser pulses, the ionized BPs first absorb one photon completing the excitation, and then absorb another photon, completing the ionization after staying in the first excited state for a period of time. The analysis of work done by the forces shows that the electric field force and quantum force play a major role in the whole ionization process. At the excitation moment and in the excitation-ionization process, the effect of the quantum force is greater than that of the electric field force. Finally, we discuss the principle of work and energy for BPs, and find that the electric field force and quantum force are non-conservative forces whose work is equal to the increment of mechanical energy of the system. In addition, it is proved that the quantum potential energy actually comes from the kinetic energy of the system and the increment of kinetic energy is equal to that of the kinetic energy of the system.

关键词： Bohmian mechanics quantum force resonance-enhanced two-photon ionization

Ionization of two-electron atom(xenon)studied by Bohmian mechanics theory

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Chinese Physics B 2020年第11期29卷 297-302页

The ionization dynamics of two-electron atom in an intense laser field is studied by the Bohmian mechanics(BM)theory, and the xenon atomic potential function is used as a model. The single ionization process and double ionization process are calculated by the BM theory and their results are in good agreement with those calculated by numerically solving the time-dependent Schrodinger equation. The analyses of the types, trajectories, and forces of Bohmian particles(BPs)undergoing the single and double ionizations indicate that the re-collision process accounts for a considerable proportion in the singly ionized cases. Furthermore, the analysis of the work done by the external force acting on the BPs shows that the quantum force plays an important role in the re-collision process. This work is helpful in understanding the ionization of two-electron atom in an intense laser field.

关键词： Bohmian mechanics quantum force atomic ionization re-collision process

Amplitude and rotation of the ellipticity of harmonics from a linearly polarized laser field

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Chinese Physics B 2022年第10期31卷 88-95页

作者： Ping Li Na Gao Rui-Xian yu jun Wang Su-yu Li Fu-Ming Guo yu-jun yang Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy(Jilin University) Changchun 130012China

We simulate the dynamic response of H^(+)_(2) in a linearly polarized laser field by numerically solving the time-dependent Schr?dinger *** elliptically polarized high-order harmonics generated by H^(+)_(2)irradiated by the linearly polarized laser field are systematically *** result shows that the amplitude and rotation of the ellipticity of harmonics are affected by the alignment angle and internuclear distance of the *** the change in forces acted on the ionized electrons and the trajectories of the electrons,the phenomena are found to be due to the change in the direction of the total Coulomb forces from the two nuclei felt by the recollided ionized electrons in the direction perpendicular to the laser polarization *** on the influence law,we can select the harmonics with a specific frequency band under different alignment angles and then synthesize the isolated attosecond pulses with different rotations,which can be continuously converted from right-handed circular polarization,linear polarization,and left-handed circular polarization by changing the alignment *** study provides a new possible approach to the real-time detection of molecular states by using attosecond pulses and obtaining more optimized harmonics with molecular properties.

关键词： high-order harmonic ellipticity rotation attosecond pulses

Dynamic stabilization of atomic ionization in a high-frequency laser field with different initial angular momenta

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Chinese Physics B 2022年第10期31卷 82-87页

作者： Di-yu Zhang yue Qiao Wen-Di Lan jun Wang Fu-Ming Guo yu-jun yang Da-jun Ding Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy(Jilin University) Changchun 130012China

We investigated the ionization of an atom with different orbital angular momenta in a high-frequency laser field by solving the time-dependent Schr¨odinger *** results showed that the ionization stabilization features changed with the relative direction between the angular momentum of the initial state and the vector field of the laser *** ionization mechanism of the atom irradiated by a high frequency was explained by calculating the transition matrix and evolution of the time-dependent wave *** study can provide comprehensive understanding to improve atomic nonadiabatic ionization.

关键词： stabilization of atomic ionization atomic initial states

Energy-efficient virtual machine consolidation algorithm in cloud data centers

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Journal of Central South University 2017年第10期24卷 2331-2341页

作者： ZHOU Zhou HU Zhi-gang yu jun-yang School of Software Central South University School of Information Technology Deakin University

Cloud data centers consume a multitude of power leading to the problem of high energy consumption. In order to solve this problem, an energy-efficient virtual machine(VM) consolidation algorithm named PVDE(prediction-based VM deployment algorithm for energy efficiency) is presented. The proposed algorithm uses linear weighted method to predict the load of a host and classifies the hosts in the data center, based on the predicted host load, into four classes for the purpose of VMs migration. We also propose four types of VM selection algorithms for the purpose of determining potential VMs to be migrated. We performed extensive performance analysis of the proposed algorithms. Experimental results show that, in contrast to other energy-saving algorithms, the algorithm proposed in this work significantly reduces the energy consumption and maintains low service level agreement(SLA) violations.

关键词： cloud computing energy consumption linear weighted method virtual machine consolidation virtual machine selection algorithm

Simultaneous study of the lower order harmonic and photoelectron emission from an atom in intense laser pulse

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Chinese Physics B 2018年第8期27卷 219-223页

作者： Yan Yan Fu-Ming Guo jun Wang Ji-Gen Chen yu-jun yang Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy（Jilin University） Changchun 130012China Department of Physics and Materials Engineering Taizhou UniversityTaizhou 318000China

We simultaneously investigate variations of a low order harmonic and photoelectron emission with an incident laser intensity by solving the time-dependent Schr6dinger equation in a momentum space. It can be found that, the intensity of low order harmonic and photoelectron are gradually enhanced with the increase of the laser intensity, when the laser frequency is not in resonance with the transition frequency between the laser-induced high excited states and the ground state. If the resonance occurs, the intensity of the lower order harmonic is reduced and the interference can be observed in the lower order photoelectron spectra.

关键词： high-order harmonic generation above threshold ionization

Quantum interference of a time-dependent wave packet of atom irradiated by an ultra-short laser pulse

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Chinese Physics B 2020年第1期29卷 223-228页

作者： Wen-Min Yan Ji-Gen Chen jun Wang Fu-Ming Guo yu-jun yang Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular SpectroscopyJilin University Changchun 130012China Zhejiang Provincial Key Laboratory for Cutting Tools Taizhou UniversityTaizhou 318000China

The wave packet evolution of an atom irradiated by an intense laser pulse is systematically investigated by using the numerical solution of the time-dependent Schr?dinger *** are two types of spatial interference structures in the time-dependent evolution of the atomic wave *** the increasing of the evolution time,the interference fringe spacing for typeⅠ(typeⅡ)becomes larger(smaller).As the wavelength of the incident laser increases,the interference of the wave packet is changed from typeⅡto typeⅠ,and the shift of interference type can be attributed to the contribution of excited states by using the energy analysis of the time-dependent wave function.

关键词： high-order harmonic generation above-threshold ionization

A Theorem of Nehari Type on the Bergman Space

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Communications in Mathematical Research 2009年第2期25卷 159-164页

作者： Lu yu-FENG yang jun Department of Applied Mathematics Dalian University of Technology Dalian 116024

In this paper we concern with the characterization of bounded linear operators S acting on the weighted Bergman spaces on the unit ball. It is shown that, if S satisfies the commutation relation STzi = Tzi（i =1,..,n）, where Tzi = zif and Tzi= P（zif） where P is the weighted Bergman projection, then S must be a Hankel operator.

关键词： Bergman space unit ball Hankel operator