Atomic Physics

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Cryogenic Be Penning trap for precision measurements with (anti-)protons (1906.09249v1)

Malte Niemann, Teresa Meiners, Johannes Mielke, Matthias Joachim Borchert, Juan Manuel Cornejo, Stefan Ulmer, Christian Ospelkaus

2019-06-21

Cooling and detection schemes using laser cooling and methods of quantum logic can contribute to high precision CPT symmetry tests in the baryonic sector. This work introduces an experiment to sympathetically cool protons and antiprotons using the Coulomb interaction with a Be ion trapped in a nearby but separate potential well. We have designed and set up an apparatus to show such coupling between two identical ions for the first time in a Penning trap. In this paper, we present evidence for successful loading and Doppler cooling of clouds and single ions. Our coupling scheme has applications in a range of high-precision measurements in Penning traps and has the potential to substantially improve motional control in these experiments.

Precision measurements on the Ba clock transition (1906.09150v1)

Kyle J. Arnold, Rattakorn Kaewuam, Sapam R. Chanu, Ting Rei Tan, Zhiqiang Zhang, Murray D. Barrett

2019-06-21

Measurement of the Ba clock transition frequency and Land`e factor are reported. The clock transition frequency , is obtained with accuracy limited by the frequency calibration of the maser used as a reference oscillator. The Land'{e} -factor for the level is determined to be , which is a 100-fold improvement on previous measurements. The -factor measurements are corrected for an ac magnetic field from trap-drive-induced currents in the electrodes, and data taken over a range of magnetic fields underscores the importance of accounting for this systematic.

Light propagation in systems involving two-dimensional atomic lattices (1906.09120v1)

Juha Javanainen, Renuka Rajapakse

2019-06-21

We study the optical response of a 2D square lattice of atoms using classical electrodynamics. Due to dipole-dipole interactions, the lattice atoms polarize as if the lattice were an atom with up to three resonance frequencies, with cooperatively shifted resonances and altered transition linewidths. We show that when the distance between two 2D lattices is large enough and Bragg reflections are absent, the lattices interact among themselves as if they radiated a plane wave whose amplitude is in accordance with the radiation from a dipole moment continuously distributed in the lattice plane. We employ these results to study light propagation in stacks of 2D lattices, drawing on simple qualitative pictures of the response of a 2D lattice and light propagation in 1D waveguides. We show that a stack of 2D lattices may emulate regularly spaced atoms in a lossless 1D waveguide, and argue that in a suitable geometry the resonance shifts characteristic of 1D and 2D lattice structures may completely cancel to eliminate density dependent resonance shifts of atoms bound to a 3D lattice. A generalization to the case of anisotropic polarizability, such as in the presence of a magnetic field, reveals light frequencies induced by the magnetic field for which the lattice is either completely transparent, or completely opaque.

Kr dating at the Guliya ice cap, Tibetan Plateau (1906.08956v1)

Lide Tian, Florian Ritterbusch, Ji-Qiang Gu, Shui-Ming Hu, Wei Jiang, Zheng-Tian Lu, Di Wang, Guo-Min Yang

2019-06-21

We present radiometric Kr dating results for ice samples collected at the outlets of the Guliya ice cap in the western Kunlun Mountains of the Tibetan Plateau. This first application of Kr dating on mid-latitude glacier ice was made possible by recent advances in Atom Trap Trace Analysis, particularly a reduction in the required sample size down to 1 L STP of krypton. Eight ice blocks were sampled from the bottom of the glacier at three different sites along the southern edges. The Kr data yield upper age limits in the range of 15-74 ka (90% confidence level). This is an order of magnitude lower than the ages exceeding 500 ka which the previous Cl data suggest for the bottom of the Guliya ice core. It is also significantly lower than the widely used chronology up to 110 ka established for the upper part of the core based on O in the ice.

Anisotropic Interactions in Electric Field Polarized Ultracold Rydberg Gases (1906.08924v1)

Akbar Jahangiri, James P. Shaffer, Luís Felipe Gonçalves, Luis Gustavo Marcassa

2019-06-21

We calculate pair potential curves for interacting Rydberg atoms in a constant electric field and use them to determine the effective dipole-dipole and van der Waals coefficients. We compare the and with experiments where the angle of a polarizing electric field is varied with respect to the axis of a quasi-1-dimensional trap at ultracold temperatures. The dipoles produced via polarization of the atoms have an angular dependent dipole-dipole interaction. We focus on the interaction potential of two rubidium Rydberg atoms in states in the blockade regime. For internuclear distances close to the blockade radius, m, molecular calculations are in much better agreement with experimental results than those based on the properties of single atoms and independent calculations of and which were used to analyze the original experiment. We find that the calculated coefficient is within of the experimental value while the coefficient is within of the experimental value.

Magnetic lattices for ultracold atoms (1906.08918v1)

Tien Duy Tran, Yibo Wang, ALex Glaetzle, Shannon Whitlock, Andrei Sidorov, Peter Hannaford

2019-06-21

This article reviews the development in our laboratory of magnetic lattices comprising periodic arrays of magnetic microtraps created by patterned magnetic films to trap periodic arrays of ultracold atoms. Recent achievements include the realisation of multiple Bose-Einstein condensates in a 10 micron-period one-dimensional magnetic lattice; the fabrication of sub-micron-period square and triangular magnetic lattice structures suitable for quantum tunnelling experiments; the trapping of ultracold atoms in a sub-micron-period triangular magnetic lattice; and a proposal to use long-range interacting Rydberg atoms to achieve spin-spin interactions between sites in a large-spacing magnetic lattice.

Optical cycling of a cold barium monofluoride beam enabled by magnetic fields (1906.08798v1)

Ralf Albrecht, Michael Scharwaechter, Tobias Sixt, Lucas Hofer, Tim Langen

2019-06-20

We demonstrate buffer-gas cooling, high-resolution spectroscopy and cycling fluorescence of cold barium monofluoride (BaF) molecules. Our source produces an intense and internally cold molecular beam containing the different BaF isotopologues with a mean forward velocity of 190 m/s. For a well-collimated beam of 138BaF we observe a flux of more than 1e10 molecules/sr/pulse in the X2Sigma, N=1 state in our downstream detection region. Studying the absorption line strength of the intermediate A'Delta state we infer a lifetime of 790+-346 ns, significantly longer than previously estimated. Finally, highly-diagonal Franck-Condon factors and magnetic remixing of dark states allow us to realize a quasi-cycling transition in 138BaF that is suitable for future laser cooling of this heavy diatomic molecule.

Floquet Heating in Interacting Atomic Gases with an Oscillating Force (1906.08747v1)

Jun-Ru Li, Boris Shteynas, Wolfgang Ketterle

2019-06-20

We theoretically investigate the collisional heating of a cold atom system subjected to time-periodic forces. We show within the Floquet framework that this heating rate due to two-body collisions has a general semiclassical expression , depending on the kinetic energy associated with the shaking, particle number density , elastic collision cross section , and an effective collisional velocity determined by the dominant energy scale in the system. We further show that the collisional heating is suppressed by Pauli blocking in cold fermionic systems, and by the modified density of states in systems in lower dimensions. Our results provide an exactly solvable example and reveal some general features of Floquet heating in interacting systems.

Transport of light through a dense ensemble of cold atoms in a static electric field (1904.06408v2)

S. E. Skipetrov, I. M. Sokolov

2019-04-03

We demonstrate that the transport of coherent quasiresonant light through a dense cloud of immobile two-level atoms subjected to a static external electric field can be described by a simple diffusion process up to atomic number densities of the order of at least atoms per wavelength cubed. Transport mean free paths well below the wavelength of light in the free space can be reached without inducing any sign of Anderson localization of light or of any other mechanism of breakdown of diffusion.

Reevaluation of the nuclear electric quadrupole moment for 87Sr by hyperfine structures and relativistic atomic theory (1906.08465v1)

Benquan Lu, Tingxian Zhang, Hong Chang, Jiguang Li, Yong Wu, Jianguo Wang

2019-06-20

The values of nuclear electric quadrupole moment are different by about 7% for 87Sr nucleus between the recommended value [N. J. Stone, At. Data Nucl. Data Tables 111-112, 1 (2016); P. Pyykko, Mol. Phys. 116, 1328 (2018)] and earlier results [e.g. A. M. Matensson-Pendrill, J. Phys. B: At. Mol. Opt. Phys. 35, 917 (2002); K. Z. Yu et al., Phys. Rev. A 70, 012506 (2004)]. In this work, we reported a new value, Q(87Sr) = 328(4) mb, making use of our calculated electric field gradients produced by electrons at nucleus in combination with experimental values for hyperfine structures of the 5s5p 3P1,2 states of the neutral Sr atom. In the framework of the multi-configuration Dirac-Hartree-Fock theory, the electron correlations were taken into account systematically so as to control the uncertainties of the electric field gradient at about 1% level. The present result is different from the recommended value, but in excellent agreement with those by Matensson-Pendrill and Yu et al.. We would recommend the present Q value as a reference for 87Sr.

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