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optical state selection process with optical pumping in a cesium atomic fountain clock

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Chinese Physics B 2021年第8期30卷 269-274页

作者： Lei Han Fang Fang Wei-Liang Chen Kun Liu Ya-Ni Zuo Fa-Song Zheng Shao-Yang Dai Tian-Chu Li School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Time and Frequency Standards National Institute of Metrology(NIM)Beijing 100029China

We propose and realize a new optical state selection method on a cesium atomic fountain clock by applying a two-laser 3-3'optical pumping configuration to spin polarize *** atoms are prepared in|F=3,mF=0>clock state with optical pumping directly after being launched up,followed by a pushing beam to push away the atoms remaining in the|F=4>*** a state selection efficiency exceeding 92%,this optical method can substitute the traditional microwave state selection,and helps to develop a more compact physical package.A Ramsey fringe has been achieved with this optical state selection method,and a contrast of 90%is obtained with a full width half maximum of 0.92 *** short-term frequency stability of 6.8×10^(-14)(τ/s)^(-1/2) is *** addition,the number of detected atoms is increased by a factor of 1.7 with the optical state selection.

关键词： optical pumping atomic fountain clock spin polarization optical state selection

A polarized^(3)He system based on metastability-exchange optical pumping

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 72-81页

作者： Yuting Wang Liangyong Wu Kaiyuan Zhang Mei Peng Siyu Chen Haiyang Yan State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Fudan UniversityShanghai 200433China Key Laboratory of Neutron Physics Institute of Nuclear Physics and ChemistryChina Academy of Engineering PhysicsMianyang 621900China

Hyperpolarized^(3)He nuclei have emerged as a significantly important approach in quantum precision measurement techniques,with extensive applications in fundamental physics,magnetometry,metrology,and *** this study,we report on the design and implementation of a^(3)He polarization system at the China Mianyang Research Reactor(CMRR),utilizing the metastabilityexchange optical pumping(MEOP)*** employed a Merritt coil system consisting of four square coils to furnish a uniform holding *** deployed a 2 W fiber laser to pump the metastable^(3)He atoms and conducted free induction decay(FID)detection of the polarized^(3)He nuclei using both pickup coil and optical *** the optical method,we used a50 m W linearly polarized distributed Bragg reflector(DBR)laser as the *** applied transverse light absorption polarimetry to measure the absolute nuclear polarization of the ground-state^(3)*** have developed cell fabrication capabilities at the CMRR,and cells at various pressures ranging from 100 to 1000 Pa have been fabricated and *** a typical borosilicate cell with 100 Pa pressure,the absolute polarization is measured as Pn≈70%,and the transverse relaxation time is estimated as T2≈0.5 ***,we constructed a few aluminosilicate cells,each carefully filled with pure^(3)He at a pressure of 100 ***,we conducted a comprehensive evaluation of their performance in the context of MEOP.

关键词： metastability exchange optical pumping polarized^(3)He magnetic resonance

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Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application—LED

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第10期10卷 1421-1427页

作者： Mohd Saiful Dzulkefly ZAN Isamu KATO Mohammad Syuhaimi AB-RAHMAN Seri Mastura MUSTAZA Department of Electrical Electronic and System EngineeringFaculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia Department of Electrical Engineering and Bioscience Waseda University

This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its *** using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer *** main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon *** the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated *** idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its *** results showed that the fabrication of the a-Si:H/SiN sample is *** effective transmission results,which accord with the polarization characteristics analysis,were obtained.

关键词： Waveguide Multilayer optical pumping Light-emitting diode (LED) Double tubed coaxial line microwave plasma chemical vapor deposition (DTCL-MPCVD)

Polarization Rotation via Asymmetric optical pumping

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Chinese Physics Letters 2014年第11期31卷 66-69页

作者：杨旭东李传亮陈峰华 School of Applied Science Taiyuan University of Science and Technology Taiyuan 030024

The polarization rotation of a linearly polarized optical （probe） field caused by a left-circularly polarized pumping beam is studied in an opened two-level system ofa STRb atom. Letting a linearly polarized optical field （probe） and left-circularly polarized pumping beams co-propagate through a Rb vapor, we observe the featurable polarization rotation signals of the linearly polarized probe field via the asymmetric optical pumping with low intensities. Based on this phenomenon, a polarization-controlled light switching can be demonstrated at a low light level Such a scheme of polarization rotation can be extended in a solid or semi-conduct material and find a practical application in al1-optical information processing.

关键词： POLARIZATION (Nuclear physics) optical pumping RUBIDIUM optical information processing LASER beams

Effect of optical pumping on the momentum relaxation time of graphene in the terahertz range

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Chinese Physics B 2013年第9期22卷 579-582页

作者：左志高王平凌福日刘劲松姚建铨 Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology School of optical and Electronic Information Huazhong University of Science and Technology College of Precision Instrument and Opto-electronics Engineering Tianjin University

The momentum relaxation time of a photoexcited graphene in the THz frequency range has been studied by using terabertz time domain spectroscopy under optical pumping at room temperature. It is found that the momentum relaxation time of the graphene as a function of the optical pumping intensity exhibits a threshold behavior. The features of the momentum relaxation time as a function of the optical pumping intensity are also investigated. The results are useful for understanding the basic underlying physics of graphene scattering as well as finding the possible applications in carbon- based electronics.

关键词： graphene momentum relaxation time optical pumping terahertz

Improvement of the short-term stability of atomic fountain clock with state preparation by two-laser optical pumping

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Chinese Physics B 2021年第5期30卷 272-276页

作者： Lei Han Fang Fang Wei-Liang Chen Kun Liu Shao-Yang Dai Ya-Ni Zuo and Tian-Chu Li School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Time and Frequency Standards National Institute of Metrology(NIM)Beijing 100029China

To improve the signal to noise ratio(SNR)and the short-term stability of cesium atomic fountain clocks,the work of two-laser optical pumping is presented theoretically and *** short-term stability of the NIM6 fountain clock has been improved by preparing more cold atoms in the|F=4,m_(F)=0>clock state with a shortened cycle *** π-polarized laser beams overlapped in the horizontal plane have been applied after launching,one is resonant with|F=4>→|F′=4>transition and the other is resonant with|F=3>→|F′=4>*** optical pumping,the population accumulated in the|m_(F)=0>clock state is improved from 11%to 63%,and the detection signal is increased by a factor of 4.2,the SNR of the clock transition probability and the short-term stability are also improved accordingly.

关键词： optical pumping atomic fountain clock spin-polarization short-term stability

optical pumping and population transfer of nuclear-spin states of caesium atoms in high magnetic fields

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Chinese Physics B 2007年第4期16卷 998-1007页

作者：罗军孙献平曾锡之詹明星 State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics WuhanInstitute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China Center for Cold Atom Physics Chinese Academy of Sciences Wuhan 430071 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

Nuclear-spin states of gaseous-state Cs atoms in the ground state are optically manipulated using a Ti：sapphire laser in a magnetic field of 1.516 T, in which optical coupling of the nuclear-spin states is achieved through hyperfine interactions between electrons and nuclei. The steady-state population distribution in the hyperfine Zeeman sublevels of the ground state is detected by using a tunable diode laser. Furthermore, the state population transfer among the hyperfine Zeeman sublevels, which results from the collision-induced modification δa（S·I） of the hyperfine interaction of Cs in the ground state due to stochastic collisions between Cs atoms and buffer-gas molecules, is studied at different buffer-gas pressures. The experimental results show that high-field optical pumping and the small change δa（S · I） of the hyperfine interaction can strongly cause the state population transfer and spin-state interchange among the hyperfine Zeeman sublevels. The calculated results maybe explain the steady-state population in hyperfine Zeeman sublevels in terms of rates of optical-pumping, electron-spin flip, nuclear spin flip, and electron-nuclear spin flip-flop transitions among the hyperfine Zeeman sublevels of the ground state of Cs atoms. This method may be applied to the nuclear-spin-based solid-state quantum computation.

关键词： high magnetic field optical pumping hyperfine interaction changing nuclear-spin and electron spin state

Transport Properties of Two Coupled Quantum Dots Under optical pumping

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Journal of Semiconductors 2006年第4期27卷 598-603页

作者：葛传楠温俊彭菊王伯根南京大学物理系固体微结构国家实验室南京210093

Using the Keldysh-Green function,we present a theoretical study on the electron transport properties of two coupled quantum dots under optical pumping. Plateaus in the I-V curve and resonant peaks in the transmission coefficient occur and can be explained by the local electron density of states in the quantum dots. The effects of the optical pumping frequency and intensity on the transport properties of the system are also discussed. The electron dynamical localization phenomenon occurs when the optical pumping frequency is equal to the discrete hole energy level. This result can be used to realize optical control switches.

关键词： Keldysh-Green function optical pumping quantum dot electron transport dynamical localization

Broadband Vibrational Cooling of Cold Cesium Molecules： Theory and Experiments

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Chinese Journal of Chemical Physics 2009年第2期22卷 149-156页

作者： D. Sofikitis A. Fioretti S. Weber M. Viteau A. Chotia R. Horchani M. Allegrini B. Chatel D. Comparat P. Pillet Laboratoire Aimé Cotton CNRS Université Paris-Sud Bat. 505 91405 Orsay France Laboratoire Collisions Agrégats Réactivité (UMR 5589 CNRS-Université Paul Sabatier Toulouse 3) IRSAMC Toulouse France CNISM Dipartimento di Fisica Universita di Pisa Largo Pontecorvo 356127 PISA Italy

The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample of cold molecules, initially distributed over several vibrational levels, has thus been transfered into a single selected vibrational level of the singlet X^1∑g ground electronic state. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. In this paper we briefly report the main experimental results and then address, in a detailed way by computer simulations, the perspectives for a ＂complete＂ cooling of the molecules, including also the rotational degree of freedom. Since the pumping process strongly depends on the relative shape of the ground and excited potential curves, ro-vibrational cooling through different excited states is theoretically compared.

关键词： Cold molecule optical pumping Pulse .shaping Ultrashort pulse Laser cooling