Line narrowing of electromagnetically induced transparency in Rb with a longitudinal magnetic field

Electromagnetically induced transparency (EIT) experiments in Lambda-type systems benefit from the use of hot vapor where the thermal averaging results in reducing the width of the EIT resonance well below the natural linewidth. Here, we demonstrate a technique for further reducing the EIT width in room-temperature vapor by the application of a small longitudinal magnetic field. The Zeeman shift of the energy levels results in the formation of several shifted subsystems; the net effect is to create multiple EIT dips each of which is significantly narrower than the original resonance. We observe a reduction by a factor of 3 in the D2 line of 87Rb with a field of 3.2 G.

Gel growth and dielectric studies of K. Rb and Cs perchlorates

Single crystals of K, Rb and Cs perchlorates have been grown by the counter diffusion of the respective ions and CIO4 through the gel medium. Studies on nucleation, growth kinetics, morphological aspects and purity are discussed in this paper. The dielectric constant, ~b, as well as loss measured along the longest axis, exhibits an anomaly at the transition temperature, Tt, in all the three crystals. It is found that the peak values of Tt are approximately 800, 100 and 53 in K, Rb and Cs perchlorates, respectively. The dielectric anomaly and the large value of c b in the cubic phase are discussed in terms of the degree of disorder of the CIO~ group and the possible contribution from defects.

Transient response of nonlinear magneto-optic rotation in a paraffin-coated Rb vapor cell

We study resonant nonlinear magneto-optic rotation (NMOR) in a paraffin-coated Rb vapor cell as the magnetic field is swept. At low sweep rates, the nonlinear rotation appears as a narrow resonance signal with a linewidth of about ``300 mu G''(2 pi x 420 Hz). At high sweep rates, the signal shows transient response with an oscillatory decay. The decay time constant is of order 100 ms. The behavior is different for transitions starting from the lower or the upper hyperfine level of the ground state because of optical pumping effects.

Bridging the Ruddlesden–Popper and the Dion–Jacobson series of layered perovskites: synthesis of layered oxides, A2–xLa2Ti3–xNbxO10(A = K, Rb), exhibiting ion exchange

Solid solutions of the formula, A2–xLa2Ti3–xNbxO10(A = K, Rb), exist for the range 0[less-than-or-eq]x[less-than-or-eq]1.0, bridging n= 3 members of the Ruddlesden–Popper series (A2La2Ti3O10) and the Dion–Jacobson series (ALa2Ti2NbO10). For 0[less-than-or-eq]x[less-than-or-eq]0.75, the phases possess body-centred structures characteristic of the Ruddlesden–Popper phases, while the x= 1 members are isostructural with KCa2Nb3O10(A = K) and CsCa2Nb3O10(A = Rb). Protonated derivatives, H2–xLa2Ti3–xNbxO10, which are prepared by ion exchange, retain the structural difference of the parent phases. A difference in the Brønsted acidity of the protonated derivatives revealed by intercalation experiments with organic bases seems to be related to this structural difference.

Synthesis of Layered Perovskite Oxides, ACa2-xLaxNb3-xTix010 (A = K, Rb, Cs), and Characterization of New Solid Acids, HCa2-xLaxNb3-xTixOlo (0 < x d 2), Exhibiting Variable Bronsted Acidity?

Layered perovskite oxides of the formula ACa~,La,Nb3-,Ti,010 (A = K, Rb, Cs and 0 < x d 2) have been prepared. The members adopt the structures of the parent ACazNb3010. Interlayer alkali cations in the niobium-titanium oxide series can be ion-exchanged with Li+, Na+, NH4+, or H+ to give new derivatives. Intercalation of the protonated derivatives with organic bases reveals that the Bronsted acidity of the solid solution series, HC~ ~ , L ~ ,N~ ~ , T ~ ,dOep~eOnd, s on the titanium content. While the x = 1 member (HCaLaNbzTiOlo) is nearly as acidic as the parent HCazNb3010, the x = 2 member (HLazNbTizOlo) is a weak acid hardly intercalating organic bases with pKa - 11.3. The variation of acidity is probably due to an ordering of Nb/Ti atoms in the triple octahedral perovskite slabs, [Ca~,La,Nb~,Ti,0~0], such that protons are attached to NbO6 octahedra in the x = 1 member and to Ti06 octahedra in the x = 2 member.

ChemInform Abstract: Synthesis of Anion-Deficient Layered Perovskites, ACa2Nb3-xMxO10-x (A: Rb, Cs; M: Al, Fe), Exhibiting Ion-Exchange and Intercalation. Evidence for the Formation of Layered Brownmillerites, ACa2Nb2AlO9 (A: Cs, H)

Anion-deficient layered perovskite oxides of the formula, ACa2Nb3-xMxO10-x (A = Rb, Cs; M = Al, Fe) for 0 < x less-than-or-equal-to 1.0, possessing tetragonal structures similar to the parent ACa2Nb3O10, have been synthesized. The interlayer A cations in these materials are readily exchanged with protons in aqueous HNO3 to give the protonated derivatives, HCa2Nb3-xMxO10-x; the latter are solid Bronsted acids intercalating a number of organic amines including aniline (pK(a) = 4.63). The distribution of acid sites in the interlayer region of HCa2Nb2MO9 inferred from n-alkylamine intercalation suggests that oxygen vacancies and Nb/M atoms are disordered in the ACa2Nb2MO9 samples prepared at 1100-1200-degrees-C. Annealing a disordered sample of CsCa2Nb2AlO9 for a long time at lower temperatures tends to order the Nb/Al atoms and oxygen vacancies to produce octahedral (NbO6/2)-tetrahedral (AlO4/2)-octahedral (NbO6/2) layer sequence reminiscent of the brownmillerite structure.

Optical frequency metrology with an Rb-stabilized ring-cavity resonator-study of cavity-dispersion errors

We have developed a technique to measure the absolute frequencies of optical transitions by using an evacuated Rb-stabilized ring-cavity resonator as a transfer cavity. The absolute frequency of the Rb D-2 line (at 780 nm) used to stabilize the cavity is known and allows us to determine the absolute value of the unknown frequency. We study wavelength-dependent errors due to dispersion at the cavity mirrors by measuring the frequency of the same transition in the Cs D-2 line (at 852 nm) at three cavity lengths. The spread in the values shows that dispersion errors are below 30 kHz, corresponding to a relative precision of 10(-10). We give an explanation for reduced dispersion errors in the ring-cavity geometry by calculating errors due to the lateral shift and the phase shift at the mirrors, and show that they are roughly equal but occur with opposite signs. We have earlier shown that diffraction errors (due to Guoy phase) are negligible in the ring-cavity geometry compared to a linear cavity; the reduced dispersion error is another advantage. Our values are consistent with measurements of the same transition using the more expensive frequency-comb technique. Our simpler method is ideally suited for measuring hyperfine structure, fine structure, and isotope shifts, up to several hundreds of gigahertz.

Trapping of neutral Rb-87 atoms on an atomchip

We report an experiment of trapping of neutral Rb-87 atoms on a, self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We collect 3 x 10(6) Rb-87 atoms in the mirror magneto-optical trap (MOT) using the external MOT coils, and 1 X 10(5) Rb-87 atoms are transferred to U-MOT using U-shaped wire in chip and a pair of bias coils.

Phase variations and phase shift in a TE011 mode microwave cavity used for in a miniature Rb fountain frequency standard

It is the first time in China that the phase variations and phase shift of microwave cavity in a miniature Rb fountain frequency standard are studied, considering the effect of imperfect metallic walls. Wall losses in the microwave cavity lead to small traveling wave components that deliver power from the cavity feed to the walls of cavity. The small traveling wave components produce a microradian distribution of phase throughout the cavity ity, and therefore distributed cavity phase shifts need to be considered. The microwave cavity is a TE011 circular cylinder copper cavity, with round cut-hole of end plates (14mm in diameter) for access for the atomic flux and two small apertures in the center of the side wall for coupling in microwave power. After attenuation alpha is calculated, field variations in cavity are solved. The field variations of the cavity are given. At the same time, the influences of loaded quality factor QL and diameter/height (2a/d) of the microwave cavity on the phase variations and phase shift are considered. According to the phase variation and phase shift of microwave cavity we select the parameters of cavity, diameter 2a = 69.2mm, height d = 34.6mm, QL = 5000, which will result in an uncertainty delta(Delta f / f0 ) < 4.7 x 10(-17) and meets the requirement for the miniature Rb fountain frequency standard with accuracy 10(-15).

Coherent spectroscopy of the Rb-87 Fg=1 -> F-e=0 closed transition

This paper has observed linewidth narrowing of dark states in rubidium cell by using the Hanle configuration. The reduction of the coherent resonance width under the transition of Rb-87 F-g = 1 -> F-e = 0 is observed and the qualitative explanation about its mechanism is presented. Multiple subnatural width dips are obtained with a linearly polarized laser beam for the transition of Rb-87 F-g = 0, 1, 2. The feature of negative and positive slope, namely dispersionlike feature, is observed in the transmitted light.

Parametric excitation of Rb-87 atoms in a quadrupole-Ioffe-configuration trap

We have experimentally studied the parametric excitation of Rb-87 atoms in a quadrupole-Ioffe-configuration trap. The temperature of an atomic cloud and number of trapped atoms versus time and modulation frequency of the parametric excitation field have been measured. We also noticed that the contribution of atomic collisions to the energy distributions can not be ignored in the case of weak excitation, which results in a lower temperature of the atomic cloud than by Gehm [Phys. Rev. A 58, 3914 (1998)] predicted.