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population transfer by femtosecond laser pulses in a ladder-type atomic system

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Chinese Physics B 2008年第7期17卷 2522-2526页

作者：樊锡君李爱云仝殿民刘呈普 College of Physics and Electronics Shandong Normal University School of Physics and Microelectronics Shandong University Institute of Advanced Energy Kyoto University

The population transfer in a ladder-type atomic system driven by linearly polarized sech-shape femtosecond laser pulses is investigated by numerically solving Schr6dinger equation without including the rotating wave approximation （RWA）. It is shown that population transfer is mainly determined by the Rabi frequency （strength） of the driving laser field and the chirp rate, and that the ratio of the dipole moments and the pulse width also have a prominent effect on the population transfer. By choosing appropriate values of the above parameters, complete population transfer can be realized.

关键词： population transfer femtosecond laser pulses ladder-type system

population transfer of U Vapor Effected by the population of a Trapped State

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Chinese Journal of Lasers 1996年第4期B5卷 301-303+307+305-306页

作者： NING Xijing JING Chunyang LIN Fucheng(Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,P. O. Box 800-211,Shanghai 201800) Shanghai Inst of Optics and Fine Mechanics Chinese Acad of Sciences Shanghai China

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关键词： ?238)U atomic vapor population transfer trapped state

population transfer of sodium in a single analytical laser pulse

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Communications in Theoretical Physics 2022年第1期74卷 92-95页

作者： Zhenzhong Ren College of Science Binzhou UniversityShandong 256600China

The population transfer of sodium in a single analytical laser pulse was studied in three models:two-level sodium,three-level sodium and many-level *** effect of a third state on a two-level system was studied by inve... 详细信息

关键词： two-level system laser pulse population transfer

Design of control sequence of pulses for the population transfer of high dimensional spin 1/2 quantum systems

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1226-1234页

作者： Cong Shuang Lou Yuesheng Dept. of Automation Univ. of Science and Technology of China Hefei 230027 P. R. China

On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions, a radio frequency pulse sequence is designed using intuitive and half counter-intuitive sequences of pulse to transfer the population of the 3-qubit system coherently. The effectiveness of the designed control sequence is verified through the system simulation experiment of the evolution of state. In principle, the design method of the control pulse sequence proposed can be generalized to use in the quantum systems of higher dimension.

关键词： quantum system control population transfer pulse sequence design intuitive sequence half counter-intuitive sequence

Isotope Effects on Two-Photon population transfer Processes of HF and DF

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Chinese Journal of Chemical Physics 2016年第3期29卷 297-302,I0001页

作者：庞玉慧王彬彬韩永昌丛书林牛英煜大连理工大学物理与光电工程学院大连116024 大连交通大学理学院大连116028

The isotope effects of XF （X=H, D） on the population transfer process via two-photon resonance excitation are investigated by solving the time-dependent SchrSdinger equation. The vibrational levels v=0 and 2 of the ground electronic state are taken to be the initial and target states, respectively, for the two molecular systems. The influences of the field peak amplitude and pulse duration on the population transfer process are discussed in detail. The pulse duration is required to be longer than 860 fs for the DF molecule to achieve a relatively high transfer probability （more than 80%）, while the one for the HF molecule is just required to be longer than 460 fs. Moreover, the intermediate level v=1 and the higher level v=3 may play more important roles in the two-photon resonance process for the DF molecule, compared to the roles in the process for the HF molecule.

关键词： population transfer Two-photon resonance transition Isotope effects DF

Delay time dependence of wave packet motion and population transfer of four-level K_2 molecule in pump–pump–probe pulses

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Chinese Physics B 2018年第5期27卷 160-165页

作者： Zhiqiang Chang Changming Li Wei Guo Hongbin Yao School of Electrical Engineering University of South China Hengyang 421001 China State Key Laboratory of Molecular Reaction Dynamics Dalian Institute of Chemical Physics Dalian 116023 China Key Laboratory of New Energy and Materials Xinjiang Institute of Engineering Urumqi 830091 China

The effect of delay time on photoelectron spectra and state populations of a four-level ladder K2 molecule is investigated by a pump1–pump2–probe pulse via the time-dependent wave packet approach. The periodical motion of the wave packet leads to the periodical change of the photoelectron spectra. The Autler–Townes triple splitting appears at zero delay time, double splitting appears at nonzero delay time between pump1 and pump2 pulses, and no splitting appears at nonzero delay time between pump2 and probe pulses. The periodical change of the state populations with the delay time may be due to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide an important basis for realizing the optical control of molecules experimentally.

关键词： wave packet motion population transfer intense femtosecond pumpl-pump2-probe pulse four-level ladder K2 molecule

Coherence generation and population transfer in a three-level ladder system

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Chinese Physics B 2011年第5期20卷 54-60页

作者：张冰姜云王刚张理达吴金辉高锦岳 College of Physics Jilin University Key Laboratory of Coherent Light and Atomic and Molecular Spectroscopy of Educational Ministry College of Physics and Electronic Engineering Mudanjiang Teachers' College Heilongjiang Superhard Materials Key Laboratory

This work explores the effect of spontaneous emission on coherence generation and population transfer in a three- level ladder atomic system driven by two pulses in counterintuitive order. With adiabatic evolution and the weak- dephasing approximation, we find that a large coherence and population transfer can be achieved even with spontaneous decay rate. The maximum coherence and population transfer decrease with the increase of spontaneous decay rate from the highest state to intermediate state. But this effect can be compensated by shortening the pulse width and enlarging the delay time. Results show that the coherence generation and population transfer never depend on the spontaneous decay rate from the intermediate state to ground state. The validity of the analytic solution is examined by numerical calculation.

关键词： coherence population transfer spontaneous decay

Steering Vibrational population transfer via Double-∑-Type Laser Scheme

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Chinese Journal of Chemical Physics 2015年第1期28卷 43-48,I0001页

作者：李立航韩永昌丛书林大连理工大学、物理与光电工程学院大连116024

The vibrational state-selected population transfer from a highly vibrationally excited level to the ground level is of great importance in the preparation of ultra-cold molecules. By using the time-dependent quantum-wave-packet method, the population transfer dynamics is investigated theoretically for the HF molecule. A double-E-type laser scheme is proposed to transfer the population from the ｜v=16〉 level to the ground vibrational level ｜v=0〉 on the ground electronic state. The scheme consists of two steps： The first step is to transfer the population from ｜v=16〉 to ｜v=7〉 via an intermediate level ｜v=11〉, and the second one is to transfer the population from ｜v=7〉 to ｜v=0〉 via ｜v=3〉. In each step, three vibrational levels form a E-type population transfer path under the action of two temporally overlapped laser pulses. The maximal population-transfer efficiency is obtained by optimizing the laser inten- sities, frequencies, and relative delays. Cases for the pulses in intuitive and counterintuitive sequences are both calculated and compared. It is found that for both cases the population can be efficiently （over 90%） transferred from the ｜v=-16〉 level to the ｜v=0〉 level.

关键词： population transfer Wave packet dynamics Vibrational state

population transfer and coherence in the adiabatic limit by counterintuitive and intuitive pulse sequences

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Chinese Physics B 2005年第2期14卷 433-438页

作者：周艳微叶存云 OpticsInstitute ZhejiangUniversityHangzhou310027China OpticsInstitute ZhejiangUniversityHangzhou310027China//CollegeLasertekInc.HoustonTX77380USA

Two approaches of achieving population transfer and coherence are investigated for the three-level A system in the adiabatic limit. The effects of the laser pulse sequence on the population transfer efficiency and coherence are *** control of quantum state and population is studied by numerical simulation based on self-consistent set of density matrix equations. It can be seen that the counterintuitive pulse sequence is more efficient in population transfer and coherence than the intuitive one.

关键词： population transfer quantum coherence three-level A system adiabatic