Trapping of neutral rubidium with a macroscopic three-phase electric trap

We trap neutral ground-state rubidium atoms in a macroscopic trap based on purely electric fields. For this, three electrostatic field configurations are alternated in a periodic manner. The rubidium is precooled in a magneto-optical trap, transferred into a magnetic trap, and then translated into the electric trap. The electric trap consists of six rod-shaped electrodes in cubic arrangement, giving ample optical access. Up to 10;{5} atoms have been trapped with an initial temperature of around 20 microkelvin in the three-phase electric trap. The observations are in good agreement with detailed numerical simulations.     

基于磁悬浮大体积交叉光学偶极阱的Dimple光阱装载研究

三维拉曼边带冷却后的铯原子样品装载于一个磁悬浮的大体积交叉光学偶极阱中, 继续加载一个小体积的光学偶极阱后, 实现了Dimple光学偶极阱对铯原子的高效装载. 对不同磁场下磁悬浮大体积光阱的有效装载势能进行理论分析与实验测量, 得出最优化的梯度磁场和均匀偏置磁场, 获得了基于磁悬浮大体积光阱的Dimple光学偶极阱的装载势能曲线, 实现了Dimple光学偶极阱对经拉曼边带冷却后俘获在磁悬浮的大体积光阱中的铯原子样品的有效装载. 比较了Dimple光学偶极阱分别从拉曼边带冷却、大体积的交叉光阱和消除反俘获势后的磁悬浮大体积光阱装载的结果, 将俘获在磁悬浮大体积光阱中的铯原子样品装载到Dimple光学偶极阱, 铯原子样品的密度提高了约15倍.     

Trivacancy recovery and formation of a cubic symmetry defect trap on111In impurities in Ni

Using perturbed angular correlations we studied the formation of a cubic symmetry defect trap in Ni near 350 K following plastic deformation at 295 K. The trap has been identified structurally as a trivacancy trap. The evolution of the defect-free and cubic trap site populations in the course of isochronal and isothermal annealing experiments leads to the conclusion that the cubic trap forms by simple trapping, and that the capture radius of the cubic trap for additional defects is very small.     

Loading Stark-decelerated molecules into electrostatic quadrupole traps

Beams of neutral polar molecules in a low-field seeking quantum state can be slowed down using a Stark decelerator, and can subsequently be loaded and confined in electrostatic quadrupole traps. The efficiency of the trap loading process is determined by the ability to couple the decelerated packet of molecules into the trap without loss of molecules and without heating. We discuss the inherent difficulties to obtain ideal trap loading, and describe and compare different trap loading strategies. A new “split-endcap” quadrupole trap design is presented that enables improved trap loading efficiencies. This is experimentally verified by comparing the trapping of OH radicals using the conventional and the new quadrupole trap designs.     

Comparison of single-neutral-atom qubit between in bright trap and in dark trap

A single neutral atom is one of the most promising candidates to encode a quantum bit(qubit). In a real experiment, a single neutral atom is always confined in a micro-sized far off-resonant optical trap(FORT). There are generally two types of traps: red-detuned trap and blue-detuned trap. We experimentally compare the qubits encoded in "clock states" of single cesium atoms confined separately in either 1064-nm red-detuned(bright) trap or 780-nm blue-detuned(dark) trap: both traps have almost the same trap depth. A longer lifetime of 117 s and a longer coherence time of about 10 ms are achieved in the dark trap. This provides a direct proof of the superiority of the dark trap over the bright trap. The measures to further improve the coherence are discussed.     

Characterizing optical dipole trap via fluorescence of trapped cesium atoms

Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.     

A reciprocal magnetic trap for neutral atoms

A novel magnetic trap for confining ultracold neutral atoms in a ring is proposed. The magnetic trap is generated by a microfabricated ferromagnetic structure integrated on an “atom chip”. The structure is based on previously demonstrated fabrication techniques and is capable of creating tightly confining reciprocal traps with trap frequencies as large as 50 kHz. Also, the trap exhibits significantly smaller magnetic field inhomogeneities compared to other proposals for current-based reciprocal traps. The suitability of this trap for atom interferometry and the study of low dimensional ultracold systems is outlined.     

Quantum dynamics and statistics of a Bose condensate generated by an atomic laser

A self-consistent quantum theory is developed for an atomic laser utilizing cooling of atoms in a trap by the method of stimulated evaporation. The model describes the pumping and extraction of the atomic field from a trap upon its interaction with independent atomic reservoirs. The stimulated collisions between atoms in the trap, which produce a Bose condensate in the lower state of the trap, are considered. The interaction of atoms with a phonon field causes spontaneous transitions between the discrete states of the trap. Calculations performed for the three-and four-level models of the trap showed the possibility of generation of a strongly squeezed sub-Poisson Bose condensate.     

表面离子阱的衬底效应模型研究及新型离子阱设计

通过分析表面离子阱衬底的功率损失和电势损失对离子阱阱深和离子加热速率的影响,提出考虑衬底效应的阱深和离子加热速率的解析分析模型.研究发现,硅基衬底的电势损失对表面离子阱阱深的降幅达17.19%,功率损失对离子加热速率的加速达13.37%.为了降低衬底效应的不利影响,设计了衬底真空隔离结构的表面离子阱,在离子阱射频电极和直流电极间的衬底表面刻蚀出多条隔离槽,从而减小衬底的等效电导和等效电容,达到降低衬底功率和电势损失的目的.模拟结果显示,相比于一般结构,真空隔离结构的硅基表面离子阱能够使阱深加深20.22%,使衬底功率损失降低54.55%.     

Storage and adiabatic cooling of polar molecules in a microstructured trap

We present a versatile electric trap for the exploration of a wide range of quantum phenomena in the interaction between polar molecules. The trap combines tunable fields, homogeneous over most of the trap volume, with steep gradient fields at the trap boundary. An initial sample of up to 10(8), CH(3)F molecules is trapped for as long as 60 s, with a 1/e storage time of 12 s. Adiabatic cooling down to 120 mK is achieved by slowly expanding the trap volume. The trap combines all ingredients for opto-electrical cooling, which, together with the extraordinarily long storage times, brings field-controlled quantum-mechanical collision and reaction experiments within reach.     

Focusing properties of concentric piecewise cylindrical vector beam

The focusing properties of a concentric piecewise cylindrical vector beam is investigated theoretically in this paper. The beam consists of three portions with different and changeable phase retardation and polarization. Numerical simulations show that the evolution of the focal shape is very considerable by changing the radius and polarization rotation angle of each portion of the vector beam. And some interesting focal spots may occur, such as two- or three-peak focus, dark hollow focus, ring focus, and two-ring-peak focus. Corresponding gradient force patterns are also computed, and novel trap patterns, including cup shell shape trap with one trap at its each side along axis, rectangle shell shape trap with one trap at its each side, dumbbell optical trap, spherical shell optical trap, may occur, which shows that the concentric piecewise cylindrical vector beam can be used to construct controllable optical tweezers.     

Directly Trapping Atoms in a U-Shaped Magneto-Optical Trap Using a Mini Atom Chip

We experimentally demonstrate the trapping of ^85Rb atoms directly on a chip-size U-shaped magneto-optical trap （U-MOT）. The trap includes a U-shaped wire on the chip, two bias magnetic field coils and laser beams. The capture volume of the U-MOT is theoretically calculated, and the trap is experimentally realized. With 2 A current applied to the U-shaped wire and 2-Gauss horizontal bias field, more than 2 × 10^6 atoms are trapped. In contrast with an ordinary mirror-MOT, this U-MOT captures atoms directly from the background, thus the trap size is greatly reduced. Based on this mini trap scheme, it is possible to realize a chip-size atom trap array for quantum information processing.     

Effect of heating treatment on trap level distribution in polyamide 66 film electrets

The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three trap levels that respectively originate from space charge trapped in amorphous phase, interphase and crystalline phase. There is one peak that originates from space charge trapped in amorphous phase for quenched one. Using multi-point method to fit the experimental curves, the detrapping current peaks can be separated and the trap depth is obtained. The shallower trap levels trapped in amorphous phase and interphase are obviously close to the deeper trap level trapped in crystalline phase for annealed polyamide 66 as the polarization temperature increases, while the trap level distribution remains unaffected by polarization temperature for quenched one.     

Theory of modified thermally stimulated current and direct determination of trap level distribution

In order to investigate the trap level distribution in polymer films, a new method is proposed based on modified thermally stimulated current (TSC) theory and numerical calculation of the TSC measurement. In this method, a new function is defined to weight the contribution of every trap level to the external current. The demarcation energy is used to study the trap emptying process. The modified TSC theory shows that only the electrons with trap levels very close to the demarcation energy can significantly contribute to the external circuit at any instant temperature. Based on this method, the trap level distribution of the DuPont original polyimide film 100HN and nanocomposite polyimide film 100CR are investigated as an application example. The effectiveness of the method is confirmed by the experiments. The experimental results show that the trap level density in the 100CR PI films is about six times larger than that in the 100HN PI films through the investigated trap level ranges 06–1.3 eV. The increased traps in 100CR should be introduced by nanofillers, probably come from the interfaces formed between nanofillers and the polymer matrix.     

Microscopic electro-optical atom trap on an evanescent-wave mirror

We put forward the idea of a surface-mounted microscopic electro-optical atom trap. The trap is formed on an evanescent-wave atom mirror by the strongly localized static electric field of two oppositely charged transparent electrodes placed close to each other. The electrodes are embedded in a refractive-index-matched thin dielectric layer on the surface of a glass prism. In our example, the phase-space density in the trap center reaches 0.1, when the trap is loaded with atoms from a gravito-optical surface trap.Received: 16 October 2003PACS: 32.80.Pj Optical cooling of atoms; trapping - 39.25. + k Atom manipulation (scanning probe microscopy, laser cooling, etc.)     

Combined Trap and Related Experiments

The regions of stability for simultaneous storage of positive and negative ions in the Combined trap are studied. It is shown that the regions of stability for the Combined trap are significantly larger than that for the Paul trap. The possibilities of making antihydrogen by simultaneous storage of antiprotons and positron clouds in this trap are also discussed.     

~(87)Rb玻色-爱因斯坦凝聚体的快速实验制备

采用二维磁光阱产生了-个快速~(87)Rb原子流,并在高真空的三维磁光阱中实现了~(87)Rb原子的快速俘获,进一步采用射频蒸发冷却技术实现了原子云的预冷却,然后将原子转移到远失谐的光学偶极阱中蒸发得到了玻色-爱因斯坦凝聚体.实验上可以在25 s内完成三维磁光阱的装载(约1.0×10~(10)个~(87)Rb原子),然后经过16 s的冷却过程最终在光学偶极阱中获得5.0×10~5个原子的玻色-爱因斯坦凝聚体.实验重点研究了二维磁光阱的优化设计和采用蓝失谐大功率光束对四极磁阱零点的堵塞,抑制四极磁阱中原子的马约拉纳损耗,更加有效地对原子云进行预冷却.     

Linear electrodynamic trap as a tool for cleaning dusty surfaces

This work is devoted to the experimental and numerical investigations of the possibility of cleaning dusty dielectric surfaces using an electrodynamic trap. We used a linear quadrupole Paul trap and polydisperse aluminium oxide particles in our experiments. Numerical simulations were performed using Brownian and molecular dynamic methods. The phenomenon of lifting and trapping of uncharged particles placed on the glass substrate located under the trap was experimentally observed. The parameters of the trap and charges of dust particles, which are necessary for drawing them from the substrate and confining in the trap, were also estimated using numerical simulations.     

Surface Planar Ion Chip for Linear Radio-Frequency Paul Traps

We propose a surface planar ion chip which forms a linear radio frequency Paul ion trap. The electrodes reside in the two planes of a chip, and the trap axis is located above the chip surface. Its electric field and potential distribution are similar to the standard linear radio frequency Paul ion trap. This ion trap geometry may be greatly meaningful for quantum information processing.     

Atom interferometers manipulated through the toroidal trap realized by the interference patterns of Laguerre-Gaussian beams

In this paper, we proposed new constructions of atom interferometers manipulated through the toroidal trap formed by the interference patterns of two co-propagation Laguerre-Gaussian (LG) beams. The coherent splitting and merging of the atomic ensemble, which is essential for the atom interferometer, is realized by the interference pattern of two LG beams. Along the beam propagation direction, a single-well trap is evolved into a double-well trap and then recombined back into a single-well trap, which can be used to form an atom interferometer.