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The effects of surface-induced evaporative cooling on an atom chipare investigated. The evolutions of temperature, number andphase-space density of the atom cloud are measured when the atomcloud is brought close to the surface. Rapid decrease of thetemperature and number of the atoms is found when the atom-surfacedistance is < 100~μm. A gain of about a factor of five on thephase-space density is obtained. It is found that the efficiencyof the surface-induced evaporative cooling depends on theatom-surface distance and the shape of the evaporative trap. Whenthe atoms are moved very close to the surface, severe heating isobserved, which dominates when the holding time is >8~ms. It isimportant that the surface-induced evaporative cooling offers novelpossibilities for the realization of a continuous condensation,where a spatially varying evaporative cooling is required. 相似文献
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We demonstrated two experimental methods of producing andguiding pulsed atomic beams on chip. One is to trap atoms first in aU-type magneto-optical trap on the chip, then transfer them to themagnetic guide field and push them simultaneously by a continuousforce from the power imbalance of the magneto-optical trap laserbeams hence the pulsed cold atom beams are produced and move alongthe magnetic guide to the destination. The other is to trap atomsdirectly by a H-type magneto-optical trap, then push them to makethem move along the magnetic guide field, thus high rate cold atombeams can be produced and guided on the chip. 相似文献
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We develop a simple and practical scheme to apply sideband cooling to a cloud of rubidium atoms. A sample containing 4 × 10~(70) ~(87)Rb is trapped in a far red detuned optical lattice. Through optimizing the relevant parameters, i.e., laser detuning, magnetic field, polarization, and duration time, a temperature around 1.5 μK and phase space density close to 1/500 are achieved. Compared with polarization gradient cooling, the temperature decreases by around one order of magnitude. This technique could be used in high precision measurement such as atomic clocks and atom interferometer. It could also serve as a precooling means before evaporation cooling in a dipole trap, and may be a promising method of achieving quantum degeneracy with purely optical means. 相似文献
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We report on the efficient generation of cold rubidium atoms as a potential coherent atom source for atom lithography. We
successfully trapped and cooled 2.6 × 108 atoms in 5 s with a conventional magneto-optical trap simply by enlarging the diameter of the laser beam to 20 mm. The size
of the laser-cooled atom cloud was measured to be 10 × 7 × 7 mm3. The number of trapped atoms was approximately 10 times as large as that of previous typical results, while the loading time
of atoms remained the same. 相似文献
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激光冷却和捕陷中性原子③ 总被引：3，自引：1，他引：3
6 激光冷却和捕陷中性原子技术的应用 前面已经提到,激光冷却和捕获中性原子技术最主要的应用是在精密计量和超冷原子物理两个方面.在精密计量方面最为典型的是可用于原子频标的"原子喷泉"(atomic fountain)技术;而在超冷原子物理方面最为典型的是玻色-爱因斯坦凝聚(Bose-Einstein condensation)和原子波激射器(atom laser)的实现. 相似文献
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We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio. 相似文献
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<正>We propose a wire configuration to create a one-dimensional(1D) array of magnetic microtraps for trapping ultracold atoms.The configuration is formed by replacing the central part of the Z-wire pattern with a zigzag wire. We simulate the performance of this pattern by the finite element method which can take both the width and depth of the wire into consideration.The result of simulation shows that this configuration can create magnetic microtraps which can be separated and combined by changing the bias magnetic field.We manage to split the Z-wire trap and prove that a similar result can occur for the new wire configuration.The fabrication processes of the atom chip are also introduced.Finally we discuss the loading method. 相似文献
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Truscott A. G. Heckenberg N. R. Rubinsztein-Dunlop H. 《Optical and Quantum Electronics》1999,31(5-7):417-430
The free running linewidth of an external cavity grating feedback diode laser is on the order of a few megahertz and is limited by the mechanical and acoustic vibrations of the external cavity. Such frequency fluctuations can be removed by electronic feedback. We present a hybrid stabilisation technique that uses both a Fabry–Perot confocal cavity and an atomic resonance to achieve excellent short and long term frequency stability. The system has been shown to reduce the laser linewidth of an external cavity diode laser by an order of magnitude to 140 kHz, while limiting frequency excursions to 60 kHz relative to an absolute reference over periods of several hours. The scheme also presents a simple way to frequency offset two lasers many gigahertz apart which should find a use in atom cooling experiments, where hyperfine ground-state frequency separations are often required. 相似文献
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《Physics letters. A》2014,378(30-31):2034-2037
A novel method of angled incidence for diffuse laser cooling of 87Rb is presented to improve the distribution of cold atom density in an integrating sphere. The angled injection scheme could cool more atoms in the middle of the sphere compared to the previous normal injection scheme. The loading time of the cold atoms for the angled injection scheme is twice as that of the normal injection scheme. The SNR and the contrast of the detected signal would be improved in the angled injection scheme. 相似文献
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Chip-based atom interferometers bring together theadvantages of atom chips and Bose--Einstein condensates. Their centralprerequisite is that a condensate can be coherently split into twohalves with a determined relative phase. This paper demonstrates thedynamical splitting and merging of an atom cloud with two U-wires onan atom chip. Symmetrical and asymmetrical splittings are realizedby applying a bias field with dif/ferent directions andmagnitudes. The trajectories of the splitting are consistent withtheoretical calculations. The atom chip is a good candidate forconstructing an atom interferometer. 相似文献
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We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The macroscopic quadrupole magnetic trap potential is designed to be moveable by controlling the currents of the two pairs of anti-Helmholtz coils. The cold atoms are initially prepared in a standard six-beam magneto-optical trap and loaded into the macroscopic quadrupole magnetic trap, and then transported to the atom chip surface by moving the macroscopic trap potential. By means of a three-dimensional absorption imaging system, we are able to optimize the position alignment of the atom cloud in the macroscopic trap and the microchip Z-shaped wire. Consequently, with a proper magnetic transfer scheme, we load the cold atoms into the microchip Z-trap directly and efficiently. The loading efficiency is measured to be about 50%.This approach can be used to generate appropriate ultracold atoms sources, for example, for a magnetically guided atom interferometer based on atom chip. 相似文献
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This paper reports an experiment on laser cooling of 87 Rb atoms in pulsed diffuse light,which is the key step towards a compact cold atom clock.It deduces an empirical formula to simulate the pulse cooling process based on the loading of cold atoms in cooling time and the loss in the dead time,which is in agreement with the experimental data.The formula gives a reference to select the parameters for the cold atom clock. 相似文献