共查询到20条相似文献,搜索用时 15 毫秒
1.
We demonstrate a novel dual color magneto–optical trap (MOT), which uses two sets of overlapping laser beams to cool and trap 87 Rb atoms. The volume of cold cloud in the dual color MOT is strongly dependent on the frequency difference of the laser beams and can be significantly larger than that in the normal MOT with single frequency MOT beams. Our experiment shows that the dual color MOT has the same loading rate as the normal MOT, but much longer loading time, leading to threefold increase in the number of trapped atoms. This indicates that the larger number is caused by reduced light induced loss. The dual color MOT is very useful in experiments where both high vacuum level and large atom number are required, such as single chamber quantum memory and Bose–Einstein condensation (BEC) experiments. Compared to the popular dark spontaneous-force optical trap (dark SPOT) technique, our approach is technically simpler and more suitable to low power laser systems. 相似文献
2.
A cold atom source is important for quantum metrology and precision measurement. To reduce the quantum projection noise limit in optical lattice clock, one can increase the number of cold atoms and reduce the dead time by enhancing the loading rate. In this work, we realize an enhanced cold mercury atom source based on a two-dimensional (2D) magneto-optical trap (MOT). The vacuum system is composed of two titanium chambers connected with a differential pumping tube. Two stable cooling laser systems are adopted for the 2D-MOT and the three-dimensional (3D)-MOT, respectively. Using an optimized 2D-MOT and push beam, about 1.3×106 atoms, which are almost an order of magnitude higher than using a pure 3D-MOT, are loaded into the 3D-MOT for 202Hg atoms. This enhanced cold mercury atom source is helpful in increasing the frequency stability of a neutral mercury lattice clock. 相似文献
3.
We study a Zeeman slower using the magnetic field generated by a pair of coils for a magneto-optical trap. The efficiency of the Zeeman slower is shown to be dependent on the intensity and frequency detuning of the laser light for slowing the atoms. With the help of numerical analysis, optimal experimental parameters are explored.Experimentally, the optimal frequency detuning and intensity of the slowing beam are explored, and 4 × 10~7 ytterbium atoms are trapped in the magneto-optical trap. 相似文献
4.
Gabbanini C Fioretti A Lucchesini A Gozzini S Mazzoni M 《Physical review letters》2000,84(13):2814-2817
We report the first observation of translationally cold ( approximately 90 &mgr;K) Rb2 molecules. They are produced in a magneto-optical trap in their triplet ground state. The detection is performed by selective mass spectroscopy after two-photon ionization into Rb+2, resonantly enhanced through the intermediate a (3)Sigma(+)(u)-->2 (3)Pi(g) molecular band. The two rubidium isotopes present very different types of behavior that are interpreted in terms of their respective collisional properties. 相似文献
5.
We report on the observation of ultracold ground electric-state cesium molecules produced directly in a magneto- optical trap with a good signal-to-noise ratio. These molecules arise from the photoassociation of magneto-optical trap lasers and they are detected by resonantly enhanced multiphoton ionization technology. The production rate of ultracold cesium molecules is up to 4×104 s-1. We measure the characteristic time of the ground electric-state cesium molecules generated in the experiment and investigate the Cs2+ molecular ion intensity as a function of the trapping laser intensity and the ionization pulse laser energy. We conclude that the production of cold cesium molecules may be enhanced by using appropriate experimental parameters, which is useful for future experiments involving the production and trapping of ultracold ground electric-state molecules. 相似文献
6.
量子投影噪声是影响光晶格钟的一个重要参数,提高磁光阱中装载率有利于降低量子投影噪声,可提升光晶格钟的性能.针对实验所用的汞原子单腔磁光阱,本文分析并计算了磁光阱中汞原子受力情况和一维运动规律,在此基础上用随机数方法对磁光阱中汞原子三维装载进行了数值计算,获得了磁光阱中的稳态原子数,研究了磁光阱的冷却激光的光强、失谐量以及磁场梯度等参数对稳态原子数的影响,得出了获得最优装载率的实验参数.涉及的计算方法和结论对汞原子光晶格钟的实验设计具有参考价值. 相似文献
7.
在获得光致原子解吸附(light-induced atom desorption,LIAD)效应的基础上,从理论和实验方面分析了LIAD对铯原子磁光阱装载的动力学过程的影响,特别是背景原子对磁光阱的影响.通过实验获得了不同光强和照射时间下关闭解吸附光后磁光阱中铯原子的衰减过程,理论模型定量地描述了背景铯原子造成压强的变化及其对最终平衡态下真空度的影响.该研究对中性原子的长时间俘获,有效控制磁光阱中原子的装载过程具有重要意义.
关键词:
光致原子解吸附
磁光阱
激光冷却与俘获 相似文献
8.
A compact cold atom beam source based on a multistage two-dimensional magneto-optical trap (MOT) has been demonstrated and characterized. The multiple-stage design greatly reduces the overall size of the source apparatus while providing a high flux of atoms. The cold atom beam was used to load a separate MOT in ultrahigh vacuum, and we obtained an actual trap loading rate of 1.5 x 109 atoms/s while using only 20 mW of total laser power for the source. The entire source apparatus, including optics, can fit into a 4 cm x 4 cm x 13 cm volume. 相似文献
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10.
通过分析铯原子在σ~+-σ~-组态的圆偏振光照射下塞曼子能级的分布情况,构造铯原子在二维磁光阱(2D-MOT)中的受力模型,利用龙格-库塔方法求解铯原子的运动方程,实现原子束产生过程的三维模拟.得出原子束流量随小孔半径、铯原子蒸汽压、激光光强、激光失谐量、磁场梯度等的变化规律.与实验数据进行比较表明受力模型的正确性,该方法能直观模拟原子束的产生,准确揭示原子束流量随各项参数的变化规律,为实验提供理论指导. 相似文献
11.
通过分析铯原子在σ+-σ-组态的圆偏振光照射下塞曼子能级的分布情况,构造铯原子在二维磁光阱(2D-MOT)中的受力模型,利用龙格-库塔方法求解铯原子的运动方程,实现原子束产生过程的三维模拟。得出原子束流量随小孔半径、铯原子蒸汽压、激光光强、激光失谐量、磁场梯度等的变化规律。与实验数据进行比较表明受力模型的正确性, 该方法能直观模拟原子束的产生,准确揭示原子束流量随各项参数的变化规律,为实验提供理论指导。 相似文献
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U. Schlöder H. Engler U. Schünemann R. Grimm M. Weidemüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):331-340
We investigate collisional properties of lithium and cesium which are simultaneously confined in a combined magneto-optical
trap. Trap-loss collisions between the two species are comprehensively studied. Different inelastic collision channels are
identified, and inter-species rate coefficients as well as cross-sections are determined. It is found that loss rates are
independent of the optical excitation of Li, as a consequence of the repulsive Li*-Cs interaction. Li and Cs loss by inelastic inter-species collisions can completely be attributed to processes involving
optically excited cesium (fine-structure changing collisions and radiative escape). By lowering the trap depth for Li, an
additional loss channel of Li is observed which results from ground-state Li-Cs collisions changing the hyperfine state of
cesium.
Received 28 December 1998 and Received in final form 16 February 1999 相似文献
15.
A. Ridinger S. Chaudhuri T. Salez U. Eismann D. R. Fernandes K. Magalhães D. Wilkowski C. Salomon F. Chevy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):223-242
We present the design, implementation and characterization of a dual-species magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom numbers. The MOT simultaneously contains 5.2 × 109 6Li-atoms and 8.0 × 109 40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a 2D-MOT for 40K. The atom sources induce capture rates of 1.2 × 109 6Li-atoms/s and 1.4 × 109 40K-atoms/s. Trap losses due to light-induced interspecies collisions of ~65% were observed and could be minimized to ~10% by using low magnetic field gradients and low light powers in the repumping light of both atomic species. The described system represents the starting point for the production of a large-atom number quantum degenerate Fermi-Fermi mixture. 相似文献
16.
di Stefano A. Verkerk Ph. Hennequin D. 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2004,30(2):243-258
The cloud of cold atoms obtained from a magneto-optical trap is known to exhibit two types of instabilities in the regime of high atomic densities: stochastic instabilities and deterministic instabilities. In the present paper, the experimentally observed deterministic dynamics is described extensively. Three different behaviors are distinguished. All are cyclic, but not necessarily periodic. Indeed, some instabilities exhibit a cyclic behavior with an erratic return time. A one-dimensional stochastic model taking into account the shadow effect is shown to be able to reproduce the experimental behavior, linking the instabilities to a several bifurcations. Erraticity of some of the regimes is shown to be induced by noise.Received: 27 April 2004, Published online: 23 July 2004PACS:
32.80.Pj Optical cooling of atoms; trapping - 05.45.-a Nonlinear dynamics and nonlinear dynamical systems - 05.40.Ca Noise 相似文献
17.
R. Romain D. Hennequin P. Verkerk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(1):171-180
An exhaustive kinetic model for the atoms in a 1D magneto-optical trap is derived, without any approximations. It is shown that the atomic density is described by a Vlasov-Fokker-Planck equation, coupled with two simple differential equations describing the trap beam propagation. The analogy of such a system with plasmas is discussed. This set of equations is then simplified through some approximations, and it is shown that corrective terms have to be added to the models usually used in this context. 相似文献
18.
The cloud of cold atoms obtained from a magneto-optical trap is known to exhibit two types of instabilities in the regime of high atomic densities: stochastic instabilities and deterministic instabilities. In the present paper, the experimentally observed stochastic dynamics is described extensively. It is shown that it exists a variety of dynamical behaviors, which differ by the frequency components appearing in the dynamics. Indeed, some instabilities exhibit only low frequency components, while in other cases, a second time scale, corresponding to a higher frequency, appears in the motion of the center of mass of the cloud. A one-dimensional stochastic model taking into account the shadow effect is shown to be able to reproduce the experimental behavior, linking the existence of instabilities to folded stationary solutions where noise response is enhanced. The different types of regimes are explained by the existence of a relaxation frequency, which in some conditions is excited by noise.Received: 18 June 2003, Published online: 28 October 2003PACS:
32.80.Pj Optical cooling of atoms; trapping - 05.40.Ca Noise - 05.45.-a Nonlinear dynamics and nonlinear dynamical systems 相似文献
19.
Loss of cold atoms due to collisions with residual gases in free flight in a magneto-optical trap 下载免费PDF全文
The loss rate of cold atoms in a trap due to residual gas collisions differs from that in a free state after the cold atoms are released from the trap. In this paper, the loss rate in a cold rubidium-87 atom cloud was measured in a magneto-optical trap(MOT) and during its free flight. The residual gas pressure was analyzed by a residual gas analyzer, and the pressure distribution in a vacuum chamber was numerically calculated by the angular coefficient method. The decay factor, which describes the decay behavior of cold atoms due to residual gas collisions during a free flight, was calculated. It was found that the decay factor agrees well with theoretical predictions under various vacuum conditions. 相似文献
20.
Richard Montgomery 《Communications in Mathematical Physics》1995,168(3):651-675
We investigate the ground state of a two-dimensional quantum particle in a magnetic field where the field vanishes nondegenerately along a closed curve. We show that the ground state concentrates on this curve ase/h tends to infinity, wheree is the charge, and that the ground state energy grows like (e/h)2/3. These statements are true for any energy level, the level being fixed as the charge tends to infinity. If the magnitude of the gradient of the magnetic field is a constantb
0 along its zero locus, then we get the precise asymptotics(e/h)
2/3
(b
0)
2/3
E
* +O(1) for every energy level. The constantE
* .5698 is the infimum of the ground state energiesE() of the anharmonic oscillator family
. 相似文献