Andrei Derevianko

Hunting for topological dark matter with atomic clocks

A proposal for detecting dark matter originating from light fields rather than particles makes use of existing networks of atomic clocks to measure time discrepancies between clocks that are spatially separated.

Multipolar theory of blackbody radiation shift of atomic energy levels and its implications for optical lattice clocks

Blackbody radiation (BBR) shifts of the {sup 3}P{sub 0}-{sup 1}S{sub 0} clock transition in the divalent atoms Mg, Ca, Sr, and Yb are evaluated. The dominant electric-dipole contributions are computed using accurate relativistic many-body techniques of atomic structure. At room temperatures, the resulting uncertainties in the E1 BBR shifts are large and substantially affect the projected 10{sup -18} fractional accuracy of the optical-lattice-based clocks. A peculiarity of these clocks is that the characteristic BBR wavelength is comparable to the {sup 3}P fine-structure intervals. To evaluate relevant M1 and E2 contributions, a theory of multipolar BBR shifts is developed. The resulting corrections, although presently masked by the uncertainties in the E1 contribution, are required at the 10{sup -18} accuracy goal.

Single-ion nuclear clock for metrology at the 19th decimal place.

The 7.6(5) eV nuclear magnetic-dipole transition in a single 229Th3+ ion may provide the foundation for an optical clock of superb accuracy. A virtual clock transition composed of stretched states within the 5F(5/2) electronic ground level of both nuclear ground and isomeric manifolds is proposed. It is shown to offer unprecedented systematic shift suppression, allowing for clock performance with a total fractional inaccuracy approaching 1×10(-19).

High-accuracy relativistic many-body calculations of van der Waals coefficients C 6 for alkaline-earth-metal atoms

Relativistic many-body calculations of van der Waals coefficients C 6 for dimers correlating to two ground-state alkaline-earth-metal atoms at large internuclear separations are reported. The following values and uncertainties were determined: C 6 = 214(3) for Be, 627(12) for Mg, 2221(15) for Ca, 3170(196) for Sr, and 5160(74) for Ba in atomic units.

Electric dipole polarizabilities at imaginary frequencies for hydrogen, the alkali-metal, alkaline-earth, and noble gas atoms

The electric dipole polarizabilities evaluated at imaginary frequencies for hydrogen, the alkali–metal atoms, the alkaline–earth atoms, and the noble gases are tabulated along with the resulting values of the atomic static polarizabilities, the atom–surface interaction constants, and the dispersion (or van der Waals) constants for the homonuclear and the heteronuclear diatomic combinations of the atoms.

Possibility of an optical clock using the 6 {sup 1}S{sub 0}{yields}6 {sup 3}P{sub 0}{sup o} transition in {sup 171,173}Yb atoms held in an optical lattice

We report calculations assessing the ultimate precision of an atomic clock based on the 578 nm 6 {sup 1}S{sub 0}{yields}6 {sup 3}P{sub 0} transition in Yb atoms confined in an optical lattice trap. We find that this transition has a natural linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine coupling. The shift in this transition due to the trapping light acting through the lowest order ac polarizability is found to become zero at the magic trap wavelength of about 752 nm. The effects of Rayleigh scattering, multipole polarizabilities, vector polarizability, and hyperfine induced electronic magnetic moments can all be held below 1 mHz (about one part in 10{sup 18}). In the case of the hyperpolarizability, however, larger shifts due to nearly resonant terms cannot be ruled out without an accurate measurement of the magic wavelength.We report calculations designed to assess the ultimate precision of an atomic clock based on the 578 nm

Highly charged ions as a basis of optical atomic clockwork of exceptional accuracy.

6 ^1S_0 -->6 ^3P^o_0

High-accuracy calculation of the blackbody radiation shift in the 133Cs primary frequency standard

transition in Yb atoms confined in an optical lattice trap. We find that this transition has a natural linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine coupling. The shift in this transition due to the trapping light acting through the lowest order AC polarizability is found to become zero at the magic trap wavelength of about 752 nm. The effects of Rayleigh scattering, higher-order polarizabilities, vector polarizability, and hyperfine induced electronic magnetic moments can all be held below a mHz (about a part in 10^{18}), except in the case of the hyperpolarizability larger shifts due to nearly resonant terms cannot be ruled out without an accurate measurement of the magic wavelength.

Accurate relativistic many-body calculations of van der Waals coefficients C8 and C10 for alkali-metal dimers

We propose a novel class of atomic clocks based on highly charged ions. We consider highly forbidden laser-accessible transitions within the 4f(12) ground-state configurations of highly charged ions. Our evaluation of systematic effects demonstrates that these transitions may be used for building exceptionally accurate atomic clocks which may compete in accuracy with recently proposed nuclear clocks.

Anisotropic pseudopotential for polarized dilute quantum gases

The blackbody radiation (BBR) shift is an important systematic correction for the atomic frequency standards realizing the SI unit of time. Presently, there is controversy over the value of the BBR shift for the primary 133Cs standard. At room temperatures, the values from various groups differ at the 3x10(-15) level, while modern clocks are aiming at 10(-16) accuracies. We carry out high-precision relativistic many-body calculations of the BBR shift. For the BBR coefficient beta at T=300 K, we obtain beta=-(1.710+/-0.006)x10(-14), implying 6x10(-17) fractional uncertainty. While in accord with the most accurate measurement, our 0.35% accurate value is in a substantial (10%) disagreement with recent semiempirical calculations. We identify an oversight in those calculations.