A Radio-frequency Atomchip for Neutral Atoms

Present work aims to establish that a generalized notion of total noise may be used as a measure of depth of nonclassicality. Here it is shown that the minimum total noise （ Tmin ） can be used as a measure of depth of higher order squeezing. It is also shown that the Caruthers-Nieto quantum phase fluctuation parameter U, which is an indirect measure of total fluctuation in sine and cosine quantum phase operators, is a measure of depth of antibunching. As an specific example, interaction of intense laser beam with an inversion symmetric third order nonlinear medium is studied. In this physical system, existence of different nonclassical states （such as squeezing, antibunching, higher order squeezing etc. ） have already been reported by us. Present work establishes that an appropriate notion of total fluctuation can be used as a measure of nonclassicality in al these cases.     

一种简易的激光冷却和俘获87Rb原子的实验系统

介绍了一套用于Rb原子的冷却和俘获的实验装置.采用注入锁定技术,获得了波长为780 nm (单频,频率波动<2 MHz, 频率调谐范围4.5 GHz)、输出功率为60 mW的冷却光. 通过在饱和吸收上加磁场的方法,实现了冷却光的偏频(10 MHz)负失谐锁定;采用磁光阱系统,实现了原子的冷却和俘获.     

Application of Magnetically Induced Transitions of 87Rb Atoms in Coherent Optical Processes

Optics and Spectroscopy - We experimentally demonstrated that magnetically induced (MI) Fg = 1 → Fe = 3 transitions of the D2-line of 87Rb are promising for the generation of optical...     

重力对~(87)Rb冷原子四极磁阱装载的影响

文章研究了重力作用下对磁光阱中~(87)Rb原子进行偏振梯度冷却后重新四极磁阱俘获的影响。研究了竖直放置四极线圈和水平放置四极线圈两种情形下,重力对原子偏振梯度冷却后四极磁阱重新俘获过程的作用,通过原子自由飞行吸收成像,观测到了原子的振荡。分析计算了~(87)Rb原子|2,2〉态补偿重力时所需的磁场梯度B′,探究了磁场参数对于振荡现象的影响,从而选择了水平放置磁场线圈的方法,提高了原子偏振梯度冷却后四极磁阱的装载效率。     

Temperature of the Remaining Cold Atoms after Two-Step Photoionization in an ^87Rb Vapor Cell Magneto-Optical Trap

The temperature of the remaining cold ^87Rb atoms confined in a vapor cell magneto-optical trap after two-step photoionization has been measured. In the two-step photoionization process, the first excitation laser is served by the cooling laser and the second excitation laser is served by a continuous semiconductor laser with a wavelength of 450hm. The results show that the temperature of the remaining cold atoms decreases as the intensity of the second excitation laser increases. Moreover, the relationship between the temperature T and number N of the remaining cold atoms generally foliows a power law, while it deviates from the well-known T ∝ N^1/3 and the power factor is smaller than 1/3. We propose that ion-atom collisions occurring during a photoionization process strongly influence the temperature sealing law in an optiealiy dense magneto-optical trap in the presence of an ionization laser. In addition, the forced evaporative cooling due to the combined effect of the detuning of the first excitation laser and the two-step photoionization plays a role in cooling the remaining cold atoms and results in the dependence of the power factor on the detuning of the first excitation laser.     

Rb原子的激光囚禁

用饱和吸收光谱法对二极管激光器进行稳频,使激光器的有效线宽小于１ＭＨｚ,并利用声光调制器使激光的频移量得到控制,满足了激光冷却与因禁原子对激光频率生和频 量的 Ｒｂ原子的激光囚禁。     

The half-life of87Rb measured as difference between the isotopes87Rb and85Rb

The half-lifeT of⁸⁷Rb was determined by means of a 4π proportional counter using thin sources of RbCl on thin conducting backings. The total thicknessD investigated (RbCl+support) ranged from 11 to 525 μg/cm². Comparative measurements with (inactive) layers of⁸⁵RbCl showed that, in the energy range below 185 eV, RbCl layers give rise to spurious pulses. Linear extrapolation of the specific activity belowD=45 μg/cm² toD=0 yieldsT=(4.88 _?0.10 ^+0.06 )·10¹⁰ y. Previously published half-lives are discussed.     

Jaynes-Cummings Model and Trapping of Atoms

We present a semiclassical approach to thetrapping problem of atoms in the Jaynes-Cummings model.We express detuning in two ways, first by consideringdetuning as the superposition of many harmonic waves, ther other by establishing a relationshipbetween detuning and the distribution of the momentum ofatoms. In these two cases we find the appearance oftrapping atoms; we discuss the quantum chaotic movement of atoms irradiated with a stronglaser.     

Experimental Study on Double Resonance Optical Pumping Spectroscopy in a Ladder-Type System of ~(87)Rb Atoms

Double resonance optical pumping spectroscopy has an outstanding advantage of high signal-to-noise ratio, thus having potential applications in precision measurement. With the counter propagated 780 nm and 776 nm laser beams acting on a rubidium vapor cell, the high resolution spectrum of 5S_(1/2)-5P_(3/2)-5D_(5/2) ladder-type transition of ~(87)Rb atoms is obtained by monitoring the population of the 5S_(1/2) ground state. The dependence of the spectroscopy lineshape on the probe and coupling fields are comprehensively studied in theory and experiment.This research is helpful for measurement of fundamental physical constants by high resolution spectroscopy.     

Simultaneous Magneto-Optical Trapping of Fermionic ^40K and Bosonic ^87Rb Atoms

We report on simultaneous magneto-optical trapping of fermionic ^40K and bosonic 87Rb atoms. This trap is the first step towards quantum degenerate fermi gas ^40K. Laser lights for the two-species magneto-optical trap （MOT） are generated from diode lasers and tapered amplifier. The enriched ^40K dispenser is utilized in the experimental setup. We obtain up to 10^7 -10^8 ^40K and 10^8 -10^9 ^87Rb atoms respectively in the steady-state single-species MOT.     

Die Halbwertszeit des Rb87

The half-life of Rb⁸⁷ was measured by the following method: NaJ(Tl)+RbJ- and CsJ(Tl)+RbJ-scintillation crystals were grown containing 1.13 and 13 weightpercent RbJ resp. The integral counting rates of these crystals were determined by extrapolation of the integral spectrum from 4 keV (NaJ(Tl)) and 6 keV (CsJ(Tl)) to sero energy. Then these crystals were pulverized, and the powder was counted in layers of saturation thickness in a Methan flow counter. The counting rates of the flow counter were attached to the Rb-contents of the layers by measuring mixtures of NaJ(Tl)+RbJ- and CsJ(Tl)+RbJ-powder of known compositions. By this procedure we determined the specific activity of natural Rubidium at (744±15) cps/g and the half-life of Rb⁸⁷ at (5.80±0.12) 10¹⁰ years. This result agrees with other determinations obtained with scintillation crystals, but disagrees with results obtained with counter tubes and geological determinations.     

Die Form des β-Spektrums des87Rubidiums bei niedrigen Energien,gemessen als Differenz an den Isotopen87Rb und85Rb

The β-spectrum of⁸⁷Rb was measured in a 4 π-proportional counter with very thin sources and backings from 0 to 90 keV. In this region we found more β-particles than other authors. The results confine the nuclear parameters to smaller limits than before. The countings up to 90 keV together with the results of other authors at higher energies lead to an estimated half life between 4.8 and 5.1 · 10¹⁰ years.     

激发态Rb原子间的碰撞能量转移

脉冲激光器激发Rb原子到5P_1/2态,通过碰撞能量转移Rb(5P_1/2)+Rb(5S_1/2)Rb(5P_3/2)+Rb(5S_1/2)产生5P_3/2原子,研究了5P_1/2+5P_1/2,5P_3/2+5P_3/2,5P_1/2+5P_3/2的碰撞能量合并产生态的过程。5P_1/2态原子密度利用Rb空心阴极灯通过光学吸收方法得到,而5P_3/2态密度通过5P_3/25S_1/2(D2线)与5P_1/25S_1/2(D₁线)跃迁的荧光比得到。因为5P_3/2+5P_3/2或5P_1/2+5P_3/2的能量和与5D态的能量差远小于5P_1/2+5P_1/2与5D态的能量差,因此5P_3/2+5P_3/2,5P_1/2+5P_3/2的过程将影响5P_1/2+5P_1/2的测量结果。由于精细结构能量转移的时间比5D态寿命小得多,故5P_1/2+5P_1/2,5P_1/2+5P_3/2和5P_3/2+5P_3/2产生的5D5P荧光是同时产生的。在不同的池温下测量了积分荧光信号的相对强度,5P态原子有效寿命由辐射陷获的理论得到,结合激发态原子密度得到了5P_1/2+5P_1/2,5P_1/2+5P_3/2和5P_3/2+5P_3/2碰撞能量合并截面分别为7.810-15,2.9×10-14和3.1×10-14 cm2。结果表明5P_1/2+5P_3/2与5P_3/2+5P_3/2产生5D_3/2态的截面基本是相等的。     

The low-lying level structure of87Rb

The low-lying states of⁸⁷Rb are studied in the framework of a quasiparticle-core coupling model. The agreement between the calculated and experimental level spectra, stripping strength, ground state static electromagnetic moments and theE2 transition rate of the first excited state is good. Electromagnetic moments and transition rates for other excited states are predicted.     

Progress of the 87Rb Fountain Clock

A fountain atomic clock based on cold 87Rb atoms has been in operation in our laboratory for several months. We therefore report the design of the rubidium fountain clock including its physical package, optical system and daily operation. Ramsey fringes have been attained with the signal to noise ratio of about 100.     

Trapping of Rb atoms by ac electric fields

We demonstrate trapping of an ultracold gas of neutral atoms in a macroscopic ac electric trap. Three-dimensional confinement is obtained by switching between two saddle-point configurations of the electric field. Stable trapping is observed in a narrow range of switching frequencies around 60 Hz. The dynamic confinement of the atoms is directly visualized at different phases of the ac switching cycle. We observe about 10(5) Rb atoms in the 1 mm3 large and several microkelvins deep trap with a lifetime of approximately 5 s.     

利用原子芯片上Z形磁阱囚禁中性87Rb原子

利用解析和数值方法计算了Z形磁阱的囚禁势,发现当囚禁中心和芯片表面距离较远时(该距离和Z形线中部导线的一半长度相差不超过一个量级),势阱的深度不能近似表示成偏置磁场By对应的能量,而要减去囚禁中心的势能高度;而增加By进行磁阱压缩到一定值时,势阱深度反而会下降.此外介绍了原子芯片的制作方法,以及利用原子芯片上Z形磁阱囚禁中性87Rb原子的实验装置和实验过程.最终有2×106个87Rb原子被转移到Z形磁阱中.     

Incommensurate CDW in Rb0.3MoO3: 87Rb NMR

The ⁸⁷Rb NMR measurement was carried out in a single-crystal Rb_0.3MoO₃. Below 180 K the NMR line well characterized the existence of incommensurate CDW. The absence of lock-in transition was confirmed from the temperature dependence of line shape. The CDW held the incommensurate phase even at 77 K, in spite of the nearly commensurate value of CDW wave vector observed in the neutron diffraction experiment. The CDW amplitude obtained from NMR was consistent with the BCS curve.