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Chinese Physics B 2008年第2期17卷 456-461页

作者：徐晓波刘金明于鹏飞 key laboratory of optical and magnetic resonance spectroscopy Department of PhysicsEast China Normal University

Taking the intrinsic decoherence effect into account, this paper investigates the entanglement of a two-qubit anisotropic Heisenberg XYZ model in the presence of nonuniform external magnetic fields by employing the concurrence as entanglement measure. It is found that both the intrinsic decoherence and the anisotropy of the system give a significant suppression to the entanglement. Moreover it finds that the initial state of the system plays an important role in the time evolution of the entanglement, which means that the entanglement of the system is independent of the nonuniformity and uniformity of the magnetic field when the system is in the initial state ｜ψ （0）） = ｜00） and [ψ′ （0）） = m ｜01）＋ n ｜10）, respectively.

关键词： Heisenberg XYZ chain concurrence magnetic field intrinsic decoherence

Quantum key distribution in 50-km optic fibers

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Science China(Physics,Mechanics & Astronomy) 2004年第2期47卷 182-188页

作者： ZHOU Chunyuan WU Guang CHEN Xiuliang LI Hexiang ZENG Heping key laboratory of optical and magnetic resonance spectroscopy and Department of Physics East China Normal University Shanghai 200062 China Key Laboratory of Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal University Shanghai 200062 China Key Laboratory of Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal University Shanghai 200062 China Key Laboratory of Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal University Shanghai 200062 China Key Laboratory of Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal University Shanghai 200062 China

In this paper, we report our recent experiment of long-distance fiber-optic plug and play quantum cryptography system wherein a Faraday-Mirror was used to compensate for the polarization mode dispersion and phase drifts. The pulse-biased coincident gate single-photon detection technique was used to effectively reduce the noises from the detrimental Rayleigh backscattering. We have achieved a quantum key distribution system with the working distance of 50 km, which was tested to be stable in more than 6 hours continuous work. And we also demonstrated the practical quantum communication in a local area network using the TCP protocol.

关键词： quantum cryptography, single-photon interference, polarization mode dispersion, phase- modula.

magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

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Chinese Optics Letters 2006年第9期4卷 497-500页

作者：刘泱恽旻印建平 key laboratory for optical and magnetic resonance spectroscopy Department of Physics East China Normal University key laboratory for optical and magnetic resonance spectroscopy Department of Physics East China Normal University

A new scheme to realize a two-dimensional （2D） array of magnetic micro-lenses for a cold atomic beam. formed by an array of square current-carrying wires, is proposed. We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms, and study the dynamic focusing processes of cold atoms passing through the mag- netic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method. The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam, even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.

关键词： magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

Study on the interaction of anticancer drug mitoxantrone with DNA by fluorescence and Raman spectroscopies

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Chinese Optics Letters 2006年第2期4卷 101-104页

作者：汤玲娟孙真荣郭建宇王祖赓 key laboratory of optical and magnetic resonance spectroscopy (East China Normal University)

Mitoxantrone, a clinically useful antitumour antibiotic for leukaemia and breast cancer, has received more attentions. In this paper, the interaction between mitoxantrone and calf thymus DNA is investigated by Raman and fluorescence spectroscopies, and the binding site of mitoxantrone to calf thymus DNA is explored. The results showed that mitoxantrone interacts with calf thymus DNA bases by the intercalation of anthracycline into the base pair plane of adenine （A） and thymine （T）, and it results in the disruption of the hydrogen bonds between calf thymus DNA bases, and thus the calf thymus DNA double-strand can be disrupted into the B-form DNA double-strand scgments.

关键词： Antibiotics DNA Drug products Fluorescence Hydrogen bonds Oncology Raman spectroscopy Tumors

A Novel Gravito-optical Surface Trap for Neutral Atoms

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Chinese Physics Letters 2006年第4期23卷 822-825页

作者：解春霞王正岭印建平 key laboratory of optical and magnetic resonance spectroscopy Department of Physics East China Normal University Shanghai 200062

We propose a novel gravito-optical surface trap （COST） for neutral atoms based on one-dimensional intensity gradient cooling. The surface optical trap is composed of a blue-detuned reduced semi-Gaussian laser beam （SGB）, a far-blue-detuned dark hollow beam and the gravity field. The SGB is produced by the diffraction of a collimated Gaussian laser beam passing through the straight edge of a semi-infinite opaque plate and then is reduced by an imaging lens. We calculate the intensity distribution of the reduced SGB, and study the dynamic process of the SGB intensity-gradient induced Sisyphus cooling for ^87Rb atoms by using Monte Carlo simulations. Our study shows that the proposed GOST can be used not only to trap cold atoms loaded from a standard magneto-optical trap, but also to cool the trapped atoms to an equilibrium temperature of 3.47μK from ～120μK, even to realize an all-optical two-dimensional Bose-Einstein condensation by using optlcal-potential evaporative cooling.

关键词： BEAM

Vacuum-Induced Quantum Interference in a Trapped Λ-Configuration Three-Level System

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Chinese Physics Letters 2005年第11期22卷 2820-2823页

作者：王正岭印建平 key laboratory of optical and magnetic resonance spectroscopy Department of Physics East China Normal University Shanghai 200062

In consideration of quantization of centre-of-mass motion, we derive the second-order solution of the dynamic equation of a Λ-configuration three-level atom confined in an approximately harmonic trap by using the timedependent perturbation theory. It is found that there are a series of dark lines in the second-order probability spectrum with multi-peak structures, which is the result of the quantum interference from the same vacuum mode in the spontaneous decay process of the trapped atom from the upper level to the two nearby lower levels. Our study shows that the second-order spectrum may be modified by the oscillation frequency Ω of the trap and the frequency difference △ between two lower levels of the three-level atom, and the depth of the dark lines from the vacuum-induced quantum interference effect is strongly dependent on the above two parameters （Ω and △ ）.

关键词： Vacuum-Induced Quantum Interference in a Trapped Λ-Configuration Three-Level System

Korteweg-de Vries Description of Dark Solitons in Bose-Einstein Condensates

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Chinese Physics Letters 2001年第5期18卷 628-630页

作者： HUANG Guo-Xiang key laboratory for optical and magnetic resonance spectroscopy and Department of Physics East China Normal UniversityShanghai 200062

We investigate the dynamics of pulses in a cigar-shaped Bose-Einstein condensate with repulsive atom-atom interactions without using Thomas-Fermi *** the linear level our results give the Bogoliubov excitation spectrum for sound propagation with speed c=c0/√2,where c_(0) is the speed for the case without *** develop a Korteweg-de Vries(KdV)description for dark soliton propagation in the system and show that it is the quantum pressure that contributes the dispersion necessary for the formation of the dark solitons.

关键词： Einstein soliton propagation

Electrostatic Surface Trap for Cold Polar Molecules with a Charged Circular Wire

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Chinese Physics Letters 2007年第5期24卷 1228-1230页

作者：马慧周蓓廖斌印建平 key laboratory for optical and magnetic resonance spectroscopy (Ministry of Education) Department of Physics East China Normal University Shanghai 200062

We propose a novel scheme to trap cold polar molecules on the surface of an insulating substrate （i.e. a chip） by using an inhomogeneous electrostatic field, which is generated by the combination of a circular charged wire （a ring electrode） and a grounded metal plate. The spatial distributions of the electrostatic field from the above charged wire layout and its Stark potentials for CO molecules are calculated. Our study shows that when the voltage applied to the wire is U = 15 kV, a ring radius is R = 5 mm, the thickness of the insulating substrate is b = 5 mm, and a wire radius is r = 1mm, the maximum efficient trapping potential （i.e., as equivalent temperature） for CO molecules is greater than 141.7mK, which is high enough to trap cold polar molecules with a temperature of 50 mK in the low-field-seeking states.

关键词： Electrostatic Molecules Circular

Stark Deceleration of an Effusive Molecular Beam by a Single Semi-Gaussian Beam

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Chinese Physics Letters 2006年第10期23卷 2737-2740页

作者：尹亚玲夏勇印建平 key laboratory for optical and magnetic resonance spectroscopy of the Ministry of Education Department of Physics East China Normal University Shanghai 200062

We propose a novel scheme to decelerate a cw precooled molecular beam by using an optical Stark decelerator, which is composed of a red-detuned cw semi-Gaussian beam. The dynamical process of the optical Stark deceleration for a cw methane molecular beam is studied by Monte Carlo simulations. It is realized that the proposed optical Stark decelerator can be used to continuously slow a cw methane molecular beam with a longitudinal temperature of 30mK, and a maximum reduction in the most probable speed of 0.388m/s （corresponding to a relative change of 9.93%） can be obtained by using a single semi-Gaussian beam with a power of 500W and a maximum central intensity of about 7.96×10^7 W/cm^2.

关键词： MIRROR

Schemes for Probabilistic Teleportation of a Three-Atom GHZ Class State via Cavity QED

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Communications in Theoretical Physics 2007年第3X期48卷 435-440页

作者： WANG Yi-Cai LIU Jin-Ming key laboratory of optical and magnetic resonance spectroscopy Department of Physics East China Normal UniversityShanghai 200062 China

Using a quantum channel composed of a two-atom and a three-atom nonmaximally entangled states, we present two schemes to teleport a three-atom GHZ class state via entanglement swapping in cavity QED with different success probabilities. The schemes can be respectively realized with the large-detuned vacuum cavities and with the large-detuned thermal cavities by separate atomic measurements after we choose appropriate atom-cavity-field interaction time.

关键词： teleportation probabilistic entangled state cavity QED