Search

The Stark shift of the ytterbium (Yb) optical clock transition due to room-temperature blackbody radiation is dominated by a static Stark effect, which was recently measured to high accuracy [J. A. Sherman et al., Phys. Rev. Lett. 108, 153002 (2012)]. However, room-temperature realization of the clock at 10-18 uncertainty requires a dynamic contribution to this static approximation. This dynamic term largely depends on a single electric dipole matrix element for which theoretically and experimentally derived values disagree significantly. We determine this important matrix element by two independent methods, which yield consistent values. Along with precise radiative lifetimes of 6s6p 3P1 and 5d6s 3D1, we report the clock shift due to an ideal 300 K blackbody environment to 0.05% precision. [ABSTRACT FROM AUTHOR]

We utilize accurate experimental data available in the literature to yield bounds on the polarizabilities of the ground and first-excited states of atomic Yb. For the 6s2 1S0 ground state, we find the polarizability &agr; to be constrained to 134.4 < &agr; ≤ 144.2 in atomic units while for the 6s6p P°0 excited state, we find 280.1 < &agr; ≤ 289.9. The uncertainty in each of these values is 1.0. These constraints provide a valuable check for ab initio and semiempirical methods used to compute polarizabilities and other related properties in Yb. [ABSTRACT FROM AUTHOR]

We consider the effect of a variation on the vibrational spectrum of Sr2 in the context of a planned experiment to test the stability ofμ = me/mp using optically trapped Sr2 molecules [Zelevinsky etal, Phys. Rev. Lett. 100, 043201 (2008); Kotochigova et al, Phys. Rev. A 79, 012504 (2009)]. We find the prospective experiment to be 3 to 4 times less sensitive to fractional variation in a as it is to fractional variation in μ. Depending on the precision ultimately achieved by the experiment, this result may give justification for the neglect of a variation or, alternatively, may call for its explicit consideration in the interpretation of experimental results. [ABSTRACT FROM AUTHOR]

We consider the influence of variation in the fine structure constant u on a promising experiment proposed by DeMille et al. to search for variation in the electron-to-proton mass ratio μ 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 α as to variation in μ. For the anticipated experimental precision, this implies that the α variation may not be negligible, as previously assumed, and further suggests that the method could serve as a competitive means to search for α variation as well. [ABSTRACT FROM AUTHOR]

We identify the molecular ion NH+ as a potential candidate for probing variations in the fine-structure constant α and electron-to-proton mass ratio μ. NH+ has an anomalously low-lying excited 4Σ- state, being only a few hundred cm-1 above the ground 2Π 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 α and μ variation. This is attributable to the close proximity of the 2Π and 4Σ- states, as well as the ensuing strong spin-orbit coupling between them. Suggestions that NH+ may exist in interstellar space and recent predictions that trapped-ion precision spectroscopy will be adaptable to molecular ions make NH+ a promising system for future astrophysical and laboratory studies of α and μ variation. [ABSTRACT FROM AUTHOR]

We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine-structure constant α. 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 β was considered. We demonstrate that for heavy systems, the sensitivity to the variation of α is of the same order of magnitude as to the variation of β. Near narrow Feshbach resonances, the enhancement of the sensitivity may exceed nine orders of magnitude. [ABSTRACT FROM AUTHOR]

We evaluate the electric quadrupole moments of the ¹S0 and ³P0 clock states of 27Al+ and 115In+. To capture all dominant contributions, our analysis extends through third order of perturbation theory and includes hyperfine coupling of the electrons to both the magnetic dipole and electric quadrupole moments of the nucleus. For 27Al+, a fortuitous cancellation leads to a suppressed frequency shift. This should allow for continued improvement of the clock without special techniques to control or cancel the shift, such as the averaging schemes that are critical to other optical ion clocks. [ABSTRACT FROM AUTHOR]

We evaluate the electric quadrupole moments of the ¹S0 and ³P0 clock states of 27Al+ and 115In+. To capture all dominant contributions, our analysis extends through third order of perturbation theory and includes hyperfine coupling of the electrons to both the magnetic dipole and electric quadrupole moments of the nucleus. For 27Al+, a fortuitous cancellation leads to a suppressed frequency shift. This should allow for continued improvement of the clock without special techniques to control or cancel the shift, such as the averaging schemes that are critical to other optical ion clocks. [ABSTRACT FROM AUTHOR]

Nuclear-spin-dependent (NSD) parity-violating (PV) effects can be strongly enhanced in diatomic molecules containing heavy atoms. Future measurements are anticipated to provide nuclear anapole moments and strength constants for PV nuclear forces. In light molecules, the NSD electroweak electron-nucleus interaction may also be detected. Here we calculate NSD PV effects for molecular ions. Our calculations are motivated by rapid developments in trapping techniques for such systems at low temperatures. [ABSTRACT FROM AUTHOR]

We present ab initio calculations of the WA parameter of the P-odd spin-rotational Hamiltonian for a variety of diatomic molecules, including the group 2 and group 12 halides. The results were obtained by relativistic Dirac-Hartree-Fock and density functional theory approaches and corrected for core polarization effects. Strong enhancement of WA is found for the group 12 diatomic halides, which should be helpful in future determination of the nuclear anapole moment. [ABSTRACT FROM AUTHOR]