Engineering topics

Flambaum, V V

Publications and source records attributed to Flambaum, V V.

14 records

DOE OSTI2011

Effect of {alpha} variation on a prospective experiment to detect variation of m{sub e}/m{sub p} in diatomic molecules

We consider the influence of variation in the fine structure constant {alpha} on a promising experiment proposed by DeMille et al. to search for variation in the electron-to-proton mass ratio {mu} using diatomic molecules [DeMille et al., Phys. Rev. Lett. 100, 043202 (2008)]. The proposed experiment involves spectroscopically probing the splitting between two nearly degenerate vibrational levels supported by different electronic potentials. Here we demonstrate that this splitting may be equally or more sensitive to variation in {alpha} as to variation in {mu}. For the anticipated experimental precision, this implies that the {alpha} variation may not be negligible, as previously assumed, and further suggests that the method could serve as a competitive means to search for {alpha} variation as well.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Rotational spectrum of the molecular ion NH{sup +} as a probe for {alpha} and m{sub e}/m{sub p} variation

We identify the molecular ion NH{sup +} as a potential candidate for probing variations in the fine-structure constant {alpha} and electron-to-proton mass ratio {mu}. NH{sup +} has an anomalously low-lying excited {sup 4}{Sigma}{sup -} state, being only a few hundred cm{sup -1} above the ground {sup 2}{Pi} state. Being a light molecule, this proximity is such that rotational levels of the respective states are highly intermixed for low angular momenta. We find that several low-frequency transitions within the collective rotational spectrum experience enhanced sensitivity to {alpha} and {mu} variation. This is attributable to the close proximity of the {sup 2}{Pi} and {sup 4}{Sigma}{sup -} states, as well as the ensuing strong spin-orbit coupling between them. Suggestions that NH{sup +} may exist in interstellar space and recent predictions that trapped-ion precision spectroscopy will be adaptable to molecular ions make NH{sup +} a promising system for future astrophysical and laboratory studies of {alpha} and {mu} variation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Is there further evidence for spatial variation of fundamental constants?

Indications of spatial variation of the fine-structure constant, {alpha}, based on study of quasar absorption systems have recently been reported [J. K. Webb, J. A. King, M. T. Murphy, V. V. Flambaum, R. F. Carswell, and M. B. Bainbridge, arXiv:1008.3907.]. The physics that causes this {alpha}-variation should have other observable manifestations, and this motivates us to look for complementary astrophysical effects. In this paper we propose a method to test whether spatial variation of fundamental constants existed during the epoch of big bang nucleosynthesis and study existing measurements of deuterium abundance for a signal. We also examine existing quasar absorption spectra data that are sensitive to variation of the electron-to-proton mass ratio {mu} and x={alpha}{sup 2{mu}}g{sub p} for spatial variation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Electron-Hole Transitions in Multiply Charged Ions for Precision Laser Spectroscopy and Searching for Variations in {alpha}

We consider transitions of electron holes (vacancies in otherwise filled shells of atomic systems) in multiply charged ions that, due to level crossing of the holes, have frequencies within the range of optical atomic clocks. Strong E1 transitions provide options for laser cooling and trapping, while narrow transitions can be used for high-precision spectroscopy and tests of fundamental physics. We show that hole transitions can have extremely high sensitivity to {alpha} variation and propose candidate transitions that have much larger {alpha} sensitivities than any previously seen in atomic systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Calculation of nuclear-spin-dependent parity nonconservation in s-d transitions of Ba{sup +}, Yb{sup +}, and Ra{sup +} ions

We use correlation potential and many-body perturbation theory techniques to calculate spin-independent and nuclear-spin-dependent parts of the parity nonconserving amplitudes of the transitions between the 6s{sub 1/2} ground state and the 5d{sub 3/2} excited state of Ba{sup +} and Yb{sup +} and between the 7s{sub 1/2} ground state and the 6d{sub 3/2} excited state of Ra{sup +}. The results are presented in a form convenient for the extracting of the constants of nuclear-spin-dependent interaction (such as, e.g., anapole moment) from the measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine-structure constant {alpha}. The method used follows the ideas of Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron-to-proton mass ratio {beta} was considered. We demonstrate that for heavy systems, the sensitivity to the variation of {alpha} is of the same order of magnitude as to the variation of {beta}. Near narrow Feshbach resonances, the enhancement of the sensitivity may exceed nine orders of magnitude.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Atomic electric dipole moment induced by the nuclear electric dipole moment: The magnetic moment effect

We have considered a mechanism for inducing a time-reversal violating electric dipole moment (EDM) in atoms through the interaction of a nuclear EDM d{sub N} with the hyperfine interaction, the ''magnetic moment effect''. We have derived the operator for this interaction and presented analytical formulas for the matrix elements between atomic states. Induced EDMs in the diamagnetic atoms {sup 129}Xe, {sup 171}Yb, {sup 199}Hg, {sup 211}Rn, and {sup 225}Ra have been calculated numerically. From the experimental limits on the atomic EDMs of {sup 129}Xe and {sup 199}Hg we have placed the following constraints on the nuclear EDMs, |d{sub N}({sup 129}Xe)|<1.1x10{sup -21}|e|cm and |d{sub N}({sup 199}Hg)|<2.8x10{sup -24}|e|cm.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2011

Calculation of parity nonconservation in neutral ytterbium

We use configuration interaction and many-body perturbation theory techniques to calculate spin-independent and spin-dependent parts of the parity-nonconserving amplitudes of the transitions between the 6s{sup 2} {sup 1}S{sub 0} ground state and the 6s5d {sup 3}D{sub 1} excited state of {sup 171}Yb and {sup 173}Yb. The results are presented in a form convenient for extracting spin-dependent interaction constants (such as anapole moment) from the measurements.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Dynamic polarizabilities and magic wavelengths for dysprosium

We theoretically study dynamic scalar polarizabilities of the ground and select long-lived excited states of dysprosium, a highly magnetic atom recently laser cooled and trapped. We demonstrate that there is a set of magic wavelengths of the unpolarized lattice laser field for each pair of states, which includes the ground state and one of these excited states. At these wavelengths, the energy shift due to laser field is the same for both states, which can be useful for resolved sideband cooling on narrow transitions and precision spectroscopy. We present an analytical formula that, near resonances, allows for the determination of approximate values of the magic wavelengths without calculating the dynamic polarizabilities of the excited states.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2010

Hyperfine-mediated static polarizabilities of monovalent atoms and ions

We apply relativistic many-body methods to compute static differential polarizabilities for transitions inside the ground-state hyperfine manifolds of monovalent atoms and ions. Knowledge of this transition polarizability is required in a number of high-precision experiments, such as microwave atomic clocks and searches for CP-violating permanent electric dipole moments. While the traditional polarizability arises in the second order of interaction with the externally applied electric field, the differential polarizability involves an additional contribution from the hyperfine interaction of atomic electrons with nuclear moments. We derive formulas for the scalar and tensor polarizabilities including contributions from magnetic dipole and electric quadrupole hyperfine interactions. Numerical results are presented for Al, Rb, Cs, Yb{sup +}, Hg{sup +}, and Fr.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2010

Excitation of the Isomeric {sup 229m}Th Nuclear State via an Electronic Bridge Process in {sup 229}Th{sup +}

We consider the excitation of the nuclear transition {sup 229g}Th-{sup 229m}Th near 7.6 eV in singly ionized thorium via an electronic bridge process. The process relies on the excitation of the electron shell by two laser photons whose sum frequency is equal to the nuclear transition frequency. This scheme allows us to determine the nuclear transition frequency with high accuracy. Based on calculations of the electronic level structure of Th{sup +} which combine the configuration-interaction method and many-body perturbation theory, we estimate that a nuclear excitation rate in the range of 10 s{sup -1} can be obtained using conventional laser sources.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2010

Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions

We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant {alpha}. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest {alpha} sensitivities seen in atomic systems.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2010

Axio-electric effect

Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of axions of the energies up to 100 keV and for an arbitrary value of the axion mass. We present numerical results for atoms used in the low radioactive background searches of dark matter (e.g., Ar, Ge, and Xe), as well as an analytical formula which fits numerical calculations for the absorption cross sections and can be applied to other atoms, molecules, and condensed matter systems. Using the cross sections for the axio-electric effect, we derive the counting rates induced by solar axions and set limits on the axion coupling constants.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Enhanced sensitivity to the time variation of the fine-structure constant and m{sub p}/m{sub e} in diatomic molecules: A closer examination of silicon monobromide

Recently it was pointed out that transition frequencies in certain diatomic molecules have an enhanced sensitivity to variations in the fine-structure constant {alpha} and the proton-to-electron mass ratio m{sub p}/m{sub e} due to a near cancellation between the fine structure and vibrational interval in a ground electronic multiplet [V. V. Flambaum and M. G. Kozlov, Phys. Rev. Lett. 99, 150801 (2007)]. One such molecule possessing this favorable quality is silicon monobromide. Here we take a closer examination of SiBr as a candidate for detecting variations in {alpha} and m{sub p}/m{sub e}. We analyze the rovibronic spectrum by employing the most accurate experimental data available in the literature and perform ab initio calculations to determine the precise dependence of the spectrum on variations in {alpha}. Furthermore, we calculate the natural linewidths of the rovibronic levels, which place a fundamental limit on the accuracy to which variations may be determined.

74 ATOMIC AND MOLECULAR PHYSICS↗