The periodic magnetic cylinder tube for atom guidance： transport efficiency analysis

We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Commun. 160 72-4). In the present paper, an analytic solution of the magnetic field inside the tube is obtained and the transport efficiency of the cold atoms in the magnetic tube at different tube intensities of magnetization is discussed. The effect of the curvature of magnetic tube on the atom transport efficiency is also considered. We have found that the tube has a cooling effect on the transverse temperature of the transported atoms.     

The periodic magnetic cylinder tube for atom guidance： transport efficiency analysis

We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Commun. 160 72－4). In the present paper, an analytic solution of the magnetic field inside the tube is obtained and the transport efficiency of the cold atoms in the magnetic tube at different tube intensities of magnetization is discussed. The effect of the curvature of magnetic tube on the atom transport efficiency is also considered. We have found that the tube has a cooling effect on the transverse temperature of the transported atoms.     

A Novel Atomic Guiding Using a Blue-Detuned TE0i Mode in Hollow Metallic Waveguides

We propose a novel scheme to guide cold atoms using a blue-detuned TE01 doughnut mode in a hollow metallic aveguide, calculate the electromagnetic field distribution of the TErn mode in the hollow metallic waveguide,and compare the attenuation characters of the EH11 and TErn mode in the hollow metallic waveguide. We also alculate the optical potential of the TErn doughnut mode for two-level ^85Rb atoms and estimate the photon cattering rate. It is found that when the detuning δ = 300 GHz, the photon scattering induced heating can e neglected, and the optical potential (Umax=570 mK) of the TErn mode is high enough to load cold atoms(120μK) from a standard magneto-optical trap and to guide them in the hollow metallic waveguide, which is a esirable scheme to realize a computer-controlled atom lithography with an arbitrary pattern.     

Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam,formed by an array of square current-carrying wires,is proposed.We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms,and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method.The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam,even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.     

Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam, formed by an array of square current-carrying wires, is proposed. We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms, and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method. The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam, even to load ultracold atoms or a BBC sample into a 2D optical lattice formed by blue detuned hollow beams.     

Velocity-tunable cold Cs atomic beam from a magneto-optical trap

The construction of a two-dimensional magneto–optical trap with hollow cooling and pushing(2D-HP MOT) is reported in detail,and a velocity-tunable cold atomic beam produced by this 2D-HP MOT is demonstrated.The magneto–optical trap system,which is constructed by a transparent quartz tube,is low in price,easy to fabricate and assemble,and convenient for atomic trapping and detection.The mean axial velocity of the cold atomic beam can be tuned from 4.5 to 8 m/s,while the atomic flux remains at a level of 10~(10) atoms∕s.This cold atomic beam source can be applied in the areas of high-precision measurements based on cold atoms.     

Magnetically Guiding Atoms with Current—Carrying Conductos

We propose a novel magnetic guide for cold neutral atoms using some current-carring conductors,The spatial distributions of the magnetic fields from a V-shaped or U-shaped current-carrying coductor are calculated.and the relationship between the resulting magnetic field and the parametes of the current-carrying conductors is analysed in dtail,The result shows that these current-craaying conductors can be used to realize a single or a controllable double magnetic guide of cold atoms in the weak-field-seeking state,and to construct various atom-optical elements,and even to realize a single-mode atomic waveguiding under certain conditions.     

Realization of an 85Rb Atomic Fountain

An atomic fountain with ^85 Rb cold atoms is reported. A series of time-of-flight signals is obtained, and the measured temperature of the cold atomic cloud is about 2.4μK. It will have potential new applications in the precise measurement of fundamental constants and the proof of the Einstein＇s equivalence principle.     

Controllable Magnetic Focusing of Cold Atoms on a Chip

We propose a new lens scheme to focus cold atoms by using a controllable inhomogeneous magnetic field from a square current-carrying wire fabricated on a chip. The spatial distributions of the magnetic field are calculated, and the results show that the generated magnetic field is a two-dimensional （2D） quadrupole one and can be used to focus cold atoms or a cold atomic beam. The dynamic processes of cold atoms passing through our square wire layout and its focusing properties are studied by using Monte Carlo simulations. Our study shows that the atomic clouds can be focused effectively by our magnetic lens scheme, and the focal length of the atomic lens and its radius of focused spot can be continuously changed by adjusting the current in the wires.     

High-Fidelity Manipulation of the Quantized Motion of a Single Atom via Stern–Gerlach Splitting

We demonstrate high-fidelity manipulation of the quantized motion of a single~(87)Rb atom in an optical tweezer via microwave couplings induced by Stern–Gerlach splitting. The Stern–Gerlach splitting is mediated by polarization gradient of a strongly focused tweezer beam that functions as fictitious magnetic field gradient. The spatial splitting removes the orthogonality of the atomic spatial wavefunctions, thus enables the microwave couplings between the motional states. We obtain coherent Rabi oscillations for up to third-order sideband transitions, in which a high fidelity of larger than 0.99 is obtained for the spin-flip transition on the first order sideband after subtraction of the state preparation and detection error. The Stern–Gerlach splitting is measured at a precision of better than 0.05 nm. This work paves the way for quantum engineering of motional states of single atoms, and may have wide applications in few body physics and ultracold chemistry.     

采用四根单模光纤束实现消逝波原子(或分子)波导的理论分析

提出了一种利用四根亚微米单模光纤束实现冷原子(或冷分子)波导的新方案，计算了四光纤束内空心区域的消逝波光场及其光学囚禁势.研究表明这种蓝失谐的空心消逝波光场同样可用于实现冷原子(或冷分子)的激光波导，而且与传统的中空光纤原子波导方案相比，不仅简单方便，造价低廉，而且更容易实现冷原子物质波的高效单模波导. 关键词： 单模光纤 消逝波 原子(或分子)波导     

高频原子波导中冷原子的磁导引

建立了高频原子波导模型,分析了铷冷原子在该波导内与磁场的相互作用势。高频波导线圈输入电流,在线圈中心轴线区域的势阱深度为mK量级,在线圈的径向能对温度为100 K左右的冷原子实现囚禁。通过分析可知改变输入波导线圈的输入电流大小,可改变势场的大小。计算了进入高频原子波导的冷原子和波导磁场产生相互作用束缚力的大小。在波导轴线中心区域,原子受到的束缚力较大,最大为1.710－23 N,为原子所受重力的10倍。     

Staggered-vortex superfluid of ultracold bosons in an optical lattice

We show that the dynamics of cold bosonic atoms in a two-dimensional square optical lattice produced by a bichromatic light-shift potential is described by a Bose-Hubbard model with an additional effective staggered magnetic field. In addition to the known uniform superfluid and Mott insulating phases, the zero-temperature phase diagram exhibits a novel kind of finite-momentum superfluid phase, characterized by a quantized staggered rotational flux. An extension for fermionic atoms leads to an anisotropic Dirac spectrum, which is relevant to graphene and high-T(c) superconductors.     

一种新颖的表面空心微光阱阵列

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     

High temperature BEC with photon-like atomic polaritons

We consider the problem of high temperature (room and beyond) true Bose-Einstein condensation (BEC) of trapped ideal 1D gas of low branch (LB) atomic polaritons for the system of two-level atomic ensemble interacting with a quantized single-mode electromagnetic field in the presence of optical collisions (OC) with buffer gas atoms. We discuss the application of biconical waveguide cavity (BWC) for observing predicted effects.     

Detection and quantized conductance of neutral atoms near a charged carbon nanotube

We describe a novel single atom detector that uses the high electric field surrounding a charged single-walled carbon nanotube to attract and subsequently field-ionize neutral atoms. A theoretical study of the field-ionization tunneling rates for atomic trajectories in the attractive potential near a nanowire shows that a broadly applicable, high spatial resolution, low-power, neutral-atom detector with nearly 100% efficiency is realizable with present-day technology. Calculations also show that the system can provide the first opportunity to study quantized conductance phenomena when detecting cold neutral atoms with mean velocities less than 15 m/s.     

Laser-induced quantum adsorption of neutral atoms in dielectric surfaces

We propose an optical technique to load neutral atoms in quantum adsorption states of a dielectric surface. Considering a realistic atom–surface potential well, we show that free cold lithium atoms approaching a LiF surface may be transferred to a surface bound state of the first excited atomic state. We also discuss schemes to populate adsorption energy levels of the atomic electronic ground state, and we find that spontaneous mechanisms transfer more than 90% of the excited adsorbed atoms into vibrational levels of the fundamental adsorption potential. The lifetime of the resulting two-dimensional waveguide is calculated, considering the adatoms’ interaction with the crystal phonons. PACS 34.50.Dy; 68.43.-h; 68.35.Ja; 32.80.Pj     

Atom trap in an axicon mirror

We have realized a novel atom trap in an axicon (conical hollow) mirror, using a frequency-modulated, single-diode laser. Different spatial distributions of trapped atoms such as a ball and a ring are observed. We show that our numerical simulations are consistent with experimental results. In particular, the ring diameter is found to be approximately the separation between the mirror axis and the magnetic field axis. The axicon trap may be useful as a precooled atom source for cold atomic beams, atom funnels, and atom waveguides.     

Controlling ultracold Rydberg atoms in the quantum regime

We discuss the properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap being commonly used in ultracold atomic physics experiments. The Hamiltonian is derived, and it is demonstrated how tight traps alter the coupling of the atom to the magnetic field. We solve the underlying Schr?dinger equation of the system within a given n manifold and show that for a sufficiently large Ioffe field strength the 2n;{2}-dimensional system of coupled Schr?dinger equations decays into several decoupled multicomponent equations governing the center of mass motion. An analysis of the fully quantized center of mass and electronic states is undertaken. In particular, we discuss the situation of tight center of mass confinement outlining the procedure to generate a low-dimensional ultracold Rydberg gas.