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1.
We propose a novel scheme of optical confinement for atoms by using a concave grating reflector.The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarized illumination.Especially,the light intensity at the focal point is about 100 times higher than that of the incident light.Such a focusing optical field reflected from the curved grating structure can provide a deep potential to trap cold atoms.We discuss the feasibility of the structure serving as an optical dipole trap.Our results are as follows.(i) Van der Waals attraction potential to the surface of the structure has a low effect on trapped atoms,(ⅱ) The maximum trapping potential is ~1.14 mK in the optical trap,which is high enough to trap cold ~(87)Rb atoms from a standard magneto-optical trap with a temperature of 120 μK,and the maximum photon scattering rate is lower than 1/s.(ⅲ) Such a microtrap array can also manipulate and control cold molecules,or microscopic particles. 相似文献
2.
The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications. 相似文献
3.
Manipulation of cold atoms by an adaptable magnetic reflector 总被引:1,自引:0,他引:1
P. Rosenbusch B.V. Hall I.G. Hughes C.V. Saba E.A. Hinds 《Applied physics. B, Lasers and optics》2000,70(5):709-720
Adaptive optics for cold atoms has been experimentally realized by applying a bias magnetic field to a static magnetic mirror.
The mirror consist of a 12-mm-diameter piece of commercial videotape, having a sine wave of wavelength 25.4 μm recorded in
a single track across its width, curved to form a concave reflector with radius of curvature R=54 mm. We have studied the
performance of the mirror by monitoring the evolution of a 24 μK cloud of 85Rb atoms bouncing on it. A uniform static external magnetic field was added to the mirror field causing a corrugated potential
from which the atoms bounce with increased angular spread. The characteristic angular distribution of the surface normal is
mapped at the peak of the bounce for atoms dropped from a height of R/2 and at the peak of the second bounce for a drop height
of R/4. In a second experiment a time-dependent magnetic field was applied and the angular distribution of the cloud was measured
as a function of field frequency. In this scheme we demonstrate a corrugated potential whose time-dependent magnitude behaves
like a diffraction grating of variable depth. Finally a rotating field was added to generate a corrugated potential that moves
with a velocity given by the product of the external field rotation frequency and the videotape wavelength. This travelling
grating provides a new method of manipulation as cold atoms are transported across the surface by surfing along the moving
wave. Two theoretical methods have been developed to predict the behaviour of atoms reflecting from these stationary, variable
magnitude and moving corrugated potentials. A simple analytic theory provides excellent agreement for reflection from a stationary
corrugated potential and gives good agreement when extended to the case of a travelling grating. A Monte Carlo simulation
was also performed by brute force numeric integration of the equations of motion for atoms reflecting from all three corrugated
potential cases.
Received: 1 December 1999 / Revised version: 3 February 2000 / Published online: 5 April 2000 相似文献
4.
提出了采用四台阶相位光栅与微透镜阵列组合产生一种新颖的表面空心微光阱阵列的方案,研究了表面空心微光阱阵列的光强分布,计算了相应的光学囚禁势,并讨论了该微光阱阵列在原子分子光学中的潜在应用.研究表明当用1W的YAG激光照射时,在1cm2面积上可产生近104个空心光阱,每个光阱具有较小的囚禁体积和较大的有效光强及其强度梯度,对85Rb原子的光学囚禁势可达190μK.如此深的光阱足以囚禁冷原子或冷分子,并可用于实现全光型原子或分子玻色-爱因斯坦凝聚,甚至制备新颖的光学晶格等.
关键词:
空心光阱
冷原子或冷分子
光学晶格 相似文献
5.
6.
一种新颖的实现冷原子或冷分子囚禁的可控制光学四阱及其二维光学晶格 总被引:3,自引:3,他引:0
原子光学晶格为精确操控中性原子和研究某些基本物理问题提供了一种方法。提出了一种利用单光束照明余弦型振幅光栅与透镜组合系统实现冷原子或冷分子囚禁的可控制光学四阱新方案,计算了四阱的光强分布,讨论了从光学四阱到双阱或单阱的演化过程,并导出了光学四阱的几何参量、光强分布、强度梯度及其曲率与光学透镜系统参量间的解析关系,获得了四阱间距与光栅空间频率的关系。研究表明通过改变余弦光栅的空间频率即可实现从光学四阱到双阱或单阱的连续双向演化。 相似文献
7.
Generation of light carrying orbital angular momentum via induced coherence grating in cold atoms 总被引:1,自引:0,他引:1
We report on the generation of light carrying orbital angular momentum through Bragg diffraction into an electromagnetically induced coherence grating in a degenerate two-level system of cold cesium atoms. The induced Zeeman coherence grating is shown to contain the spatial phase structure of the incident beams. The exchange of phase information between a light beam with orbital angular momentum and a long-lived atomic coherence opens up the way to process quantum information encoded in a multidimensional state space. 相似文献
8.
Controllable optical multi-well trap and its optical lattices using compounded cosine patterns
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This paper proposes a flexible scheme to form various optical multi-well traps for cold atoms or molecules by using a simple optical system composed of an compounded amplitude cosine-only grating and a single lens illuminated by a plane light wave or a Gaussian beam.Dynamic manipulation and evolution of multi-well trap can be easily implemented by controlling the modulation frequency of the cosine patterns.It also discusses how to expand this multi-well trap to two-dimensional lattices with single-or multi-well trap by using an orthogonally or non-orthogonally modulated grating,as well as using incoherent multi-beam illumination,and these results show that all the symmetric structures of two-dimensional Bravais lattices can be obtained facilely by using proposed scheme. 相似文献
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10.
We propose some new schemes to constitute two-dimensional (2D) array of multi-well optical dipole traps for cold atoms (or molecules) by using an optical system consisting of a binary π-phase grating and a 2D array of rectangle microlens. We calculate the intensity distribution of each optical well in 2D array of multi-well traps and its geometric parameters and so on. The proposed 2D array of multi-well traps can be used to form novel 2D optical lattices with cold atoms (or molecules), and form various novel optical crystals with cold atoms (or molecules), or to perform quantum computing and quantum information processing on an atom chip, even to realize an array of all-optical multi-well atomic (or molecular) BoseEinstein condensates (BECs) on an all-optical integrated atom (or molecule) chip. 相似文献
11.
提出了一种采用Damman光栅和球面透镜组合光学系统产生二维光阱阵列的新方案. 在使用红失谐高斯激光束照射的条件下,推导了计算光阱阵列的周期、光强分布、光强梯度和光阱几何参数的经验公式,讨论了此光阱阵列的特点以及在原子光学和分子光学中的应用. 研究结果表明,这种光阱阵列方案比已有的光阱阵列方案更为简单可行、操作方便,非常适用于冷原子或冷分子的阵列囚禁,以及制备新颖的光学晶格.
关键词:
冷原子或冷分子
光阱阵列
Damman光栅
光偶极势 相似文献
12.
We demonstrate that emission-induced self-organization of two-level atoms can effect strong damping of the sample's center-of-mass motion. When illuminated by far-detuned light, cold cesium atoms assemble into a density grating that efficiently diffracts the incident light into an optical resonator. We observe random phase jumps of pi in the emitted light, confirming spontaneous symmetry breaking in the atomic self-organization. The Bragg diffraction results in a collective friction force with center-of-mass deceleration up to 1000 m/s(2) that is effective even for an open atomic transition. 相似文献
13.
液晶空间光调制器能够方便地用于制作各种衍射型光学元件, 但液晶空间光调制器存在分辨率有限的缺点, 本文提出了用液晶空间光调制器制作相位型光栅, 产生一维和二维光阱阵列的新方案, 用迭代傅里叶级数算法优化设计光栅的相位分布, 在不改变空间光调制器硬件参数设置的情况下, 充分利用和发掘了空间光调制器的优点, 同时又能较好地回避其所存在的缺陷. 根据现有的空间光调制器的技术参数, 模拟仿真设计光栅, 计算光强分布, 结果表明: 用大失谐、小功率激光照明, 能够产生具有很高峰值光强和光强梯度的光阱阵列, 囚禁冷原子的光学偶极势达到mK量级, 对原子的作用力远大于原子的重力. 相似文献
14.
We have observed the spontaneous evolution of a dense sample of Rydberg atoms into an ultracold plasma, in spite of the fact that each of the atoms may initially be bound by up to 100 cm(-1). When the atoms are initially bound by 70 cm(-1), this evolution occurs when most of the atoms are translationally cold, <1 mK, but a small fraction, approximately 1%, is at room temperature. Ionizing collisions between hot and cold Rydberg atoms and blackbody photoionization produce an essentially stationary cloud of cold ions, which traps electrons produced later. The trapped electrons rapidly collisionally ionize the remaining cold Rydberg atoms to form a cold plasma. 相似文献
15.
We have monitored the third and the fifth order nonlinear susceptibilities of cold cesium atoms confined in a magneto-optical trap through the observation of Bragg diffraction into a transferred population grating. A simple theoretical model based on a density matrix calculation in a five-level system was developed and accounts reasonably for the observed results. 相似文献
16.
P. L. Chapovsky 《JETP Letters》2007,86(2):78-82
Nonlinear optical recoil-induced resonances have been observed in a gas of cold rubidium atoms trapped in a dark magneto-optical trap. These resonances are used to measure the temperature and velocity distribution of the cold atoms. The velocity distribution of the atoms in the dark magneto-optical trap has an excessive amount of fast atoms as compared to the Maxwell distribution and to the distribution in a standard magneto-optical trap. 相似文献
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18.
A two step light emission process becomes possible when atoms are placed near a metallic grating. The atoms can excite surface plasmons in the grating. The surface plasmons can then emit light. This light is emitted at certain angles determined by momentum conservation in the plane of the grating. Thus, the angles depend on the spacing of the grating. Our measurements on light from nitrogen atoms at distances, d, ranging from 10 to 100 nm from a silver grating are in agreement with a recent theory of Aravind, Hood and Metiu. We also report the effect of a nonsinusoidal grating profile and the emission of light at angles which can be predicted from a straightforward extension of the theory. 相似文献
19.