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Field-free orientation of diatomic molecule via the linearly polarized resonant pulses

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Chinese Physics B 2015年第10期24卷 213-217页

作者：李苏宇郭福明王俊杨玉军金明星 Institute of atomic and molecular Physics Jilin University Jilin Provincial key laboratory of Applied atomic and molecular Spectroscopy Jilin University

We propose a scheme to coherently control the field-free orientation of NO molecule whose rotational temperature is above 0 K. It is found that the maximum molecular orientation is affected by two factors： one is the sum of the population of M = 0 rotational states and the other is their distribution, however, their distribution plays a much more significant role in molecular orientation than the sum of their population. By adopting a series of linearly polarized pulses resonant with the rotational states, the distribution of M = 0 rotational states is well rearranged. Though the number of pulses used is small, a relatively high orientation degree can be obtained. This scheme provides a promising approach to the achievement of a good orientation effect.

关键词： orientation diatomic molecule linearly polarized pulses coherent control

A tunable XUV monochromatic light source based on the time preserving grating selection of high-order harmonic generation

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Chinese Physics B 2017年第7期26卷 194-198页

作者：牛永梁红静刘燚刘方圆马日丁大军 Institute of atomic and molecular Physics Jilin University Jilin Provincial key laboratory of Applied atomic and molecular Spectroscopy Jilin University

We accomplish a laboratory facility for producing a femtosecond XUV coherent monochromatic radiation with a broad tunable spectral range of 20 eV-75 eV. It is based on spectral selected single-order harmonics from intense laser driven high harmonic generation in gas phase. The time preserving for the selected harmonic radiation is achieved by a Czerny-Turner type monochromator designed with a conical diffraction grating mount for minimizing the time broadening caused by grating diffraction and keeping a relatively high diffraction efficiency. Our measurement shows that the photon flux of the 23-order harmonic（H23） centered at 35.7 eV is 1×10~9 photons/s approximately with a resolving power E/？E ≈ *** source provides an ultrashort tunable monochromatic XUV beam for ultrafast studies of electronic and structural dynamics in a large variety of matters.

关键词： high harmonic generation conical diffraction time preserving monochromator femtosecond extreme ultraviolet pulse

Ellipticity-dependent ionization/dissociation of carbon dioxide in strong laser fields

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Chinese Physics B 2015年第3期24卷 122-126页

作者：张军峰马日左万龙吕航黄红卫徐海峰金明星丁大军 Institute of atomic and molecular Physics Jilin University Jilin Provincial key laboratory of Applied atomic and molecular Spectroscopy Jilin University

Ionization and dissociation of linear triatomic molecules, carbon dioxide, are studied in 50-fs 800-nm strong laser fields using time-of-flight mass spectrometer. The yields of double charged ions CO2^2＋ and various fragment ions（CO^＋,O^n＋, and C^n＋（n = 1, 2）） are measured as a function of ellipticity of laser polarization in the intensity range from 5.0 ×10^13W/cm2 to 6.0 × 10^14W/cm^2. The results demonstrate that non-sequential double ionization, which is induced by laser-driven electron recollision, dominates double ionization of CO2 in the strong IR laser field with intensity lower than2.0 × 10^14W/cm^2. The electron recollision could also have contribution in strong-field multiple ionization and formation of fragments of CO2 molecules. The present study indicates that the intensity and ellipticity dependence of ions yields can be used to probe the complex dynamics of strong-field ionization/dissociation of polyatomic molecules.

关键词： laser ellipticity strong field ionization and dissociation carbon dioxide

Deterministic Quantum key Distribution with Pulsed Homodyne Detection

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Communications in Theoretical Physics 2010年第1期53卷 67-70页

作者：王川王婉莹艾清龙桂鲁 School of Science and key laboratory of Optical Communication and Lightwave Technologies Beijing University of Posts and Telecommunications key laboratory of atomic and molecular nanosciences and Department of Physics Tsinghua University Tsinghua National laboratory of Information Science and Technology

In this paper, we propose a deterministic quantum communication protocol using weak coherent states and pulsed homodyne detection. In this protocol, the communication parties exchange their secret information deterministicaJly in two rounds. The devices and efficiency of the protocol are discussed respectively. We also show the security of the protocol against intercept-resend and Trojan-Horse eavesdropping attacks.

关键词： deterministic quantum key distribution pulsed homodyne detection

Rydberg excitation of neutral nitric oxide molecules in strong UV and near-IR laser fields

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Chinese Physics B 2015年第6期24卷 284-287页

作者：吕航张军峰左万龙徐海峰金明星丁大军 Institute of atomic and molecular Physics Jilin University Jilin Provincial key laboratory of Applied atomic and molecular Spectroscopy(Jilin University)

Rydberg state excitations of neutral nitric oxide molecules are studied in strong ultraviolet （UV） and near-infra-red （IR） laser fields using a linear time-of-flight （TOF） mass spectrometer with the pulsed electronic field ionization method. The yield of Rydberg molecules is measured as a function of laser intensity and ellipticity, and the results in UV laser fields are compared with those in near-IR laser fields. The present study provides the first experimental evidence of neutral Rydberg molecules surviving in a strong laser field. The results indicate that a rescattering-after-tunneling process is the main contribution to the formation of Rydberg molecules in strong near-IR laser fields, while multi-photon excitation may play an important role in the strong UV laser fields.

关键词： strong laser fields neutral Rydberg excitation nitric oxide

Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene in strong IR and UV laser fields

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Chinese Physics B 2015年第11期24卷 212-216页

作者：张军峰吕航左万龙徐海峰金明星丁大军 Institute of atomic and molecular Physics Jilin University Jilin Provincial key laboratory of Applied atomic and molecular Spectroscopy Jilin University

Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene are studied in linearly polarized 50-fs, 800-nm and 400-nm strong laser fields using a time-of-flight mass spectrometer. It is shown that at low laser intensity, the parent ions are dominant for any one of the molecules in an 800-nm strong laser field, while extensive fragmentation is observed in a 400-nm laser field, which can be understood by the resonant photon absorption of molecular cations. The ratio of the yield of the parent ion to the yield of the total ion for each molecule is measured as a function of laser intensity in a range from 1.0 × 1013 W/cm2 to 4.0 × 1014 W/cm2, in either the 800-nm or 400-nm laser field. The results show that the fragmentation of the aromatic molecules increases significantly as the laser intensity is increased. Possible mechanisms for fragmentation in strong laser fields are discussed. Finally, the saturation intensity of ionization of the titled molecules is also determined.

关键词： strong field ionization fragmentation benzene substitute benzene

Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls

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Communications in Theoretical Physics 2007年第7期48卷 71-74页

作者： WANG Yan-Hui LIU Xiao-Shu LONG Gui-Lu1 key laboratory for atomic and molecular nanosciences and Department of Physics,Tsinghua University,Beijing 100084,China2 Tsinghua National laboratory for Information Science and Technology,Tsinghua University,Beijing 100084,China key laboratory for atomic and molecular nanosciences and Department of Physics Tsinghua University Beijing 100084 China Tsinghua National laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

In this paper,we present decoupling bang-bang operations for the suppression of general decoherence,bothamplitude and phase damping,in a three-level system in *** give a program to design a sequence ofperiodic twinbor... 详细信息

关键词： bang-bang operation general decoherence three-level system

General Decoherence Suppression in Three-Level Atom in V-and ■-Configurations

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Communications in Theoretical Physics 2008年第4期49卷 881-886页

作者： WANG Yan-Hui LIU Xiao-Shu RUAN Dong LONG Gui-Lu key laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing 100084 China key laboratory for atomic and molecular nanosciences Tsinghua University Beijing 100084 China Tsinghua National laboratory for Information Science and Technology Beijing 100084 China

In this paper, we present the decoupling bang-bang （BB） twin-born pulses to suppress the genera/deco- herence, both amplitude and phase decoherence, in a three-level atom in V- and Ξ-configurations. We give the exa... 详细信息

关键词： decoherence suppression quantum information processing

Creation of Entanglement with Nonlocal Operations

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Communications in Theoretical Physics 2005年第4X期44卷 625-630页

作者： ZHANG Yong CAO Wan-Cang LONG Gui-Lu key laboratory for Quantum Information and Measurements Department of Physics Tsinghua University Beijing 100084 China key laboratory for atomic and molecular nanosciences Tsinghua University Beijing 100084 China Department of Physics Chifeng College Chifeng 024000 China

We discuss how to create more entanglement with nonlocal operations acting on two-particle states. For a given nonlocal operation, we find that some input states cannot produce entanglement and some produce the maximal entanglement, and find that any initial entangled states can produce more entanglement than initial product states.

关键词： nonlocal operation entanglement entropy