44 research outputs found
Ion clock and search for the variation of the fine structure constant using optical transitions in Nd and Sm
We study ultranarrow - transitions in Nd and
Sm and demonstrate that they lie in the optical region. The transitions
are insensitive to external perturbations. At the same time they are sensitive
to the variation of the fine structure constant . The fractional
accuracy of the frequency of the transitions can be smaller than ,
which may provide a basis for atomic clocks of superb accuracy. Sensitivity to
the variation of approaches per year.Comment: 4 pages, 2 tables, no figure
Magic frequencies for cesium primary frequency standard
We consider microwave hyperfine transitions in the ground state of cesium and
rubidium atoms which are presently used as the primary and the secondary
frequency standards. The atoms are confined in an optical lattice generated by
a circularly polarized laser field. We demonstrate that applying an external
magnetic field with appropriately chosen direction may cancel dynamic Stark
frequency shift making the frequency of the clock transition insensitive to the
strengths of both the laser and the magnetic fields. This can be attained for
practically any laser frequency which is sufficiently distant from a resonance.Comment: 4 pages, 2 figure
Possibility of "magic" co-trapping of two atomic species in optical lattices
Much effort has been devoted to removing differential Stark shifts for atoms
trapped in specially tailored "magic" optical lattices, but thus far work has
focused on a single trapped atomic species. In this work, we extend these ideas
to include two atomic species sharing the same optical lattice. We show
qualitatively that, in particular, scalar J = 0 divalent atoms paired with
non-scalar state atoms have the necessary characteristics to achieve such Stark
shift cancellation. We then present numerical results on "magic" trapping
conditions for 27Al paired with 87Sr, as well as several other divalent atoms.Comment: 5 pages, 2 figures, 1 tabl
Core-valence correlations for atoms with open shells
We present an efficient method of inclusion of the core-valence correlations
into the configuration interaction (CI) calculations. These correlations take
place in the core area where the potential of external electrons is
approximately constant. A constant potential does not change the core electron
wave functions and Green's functions. Therefore, all operators describing
interaction of valence electrons and core electrons (the core part of
the Hartree-Fock Hamiltonian
, the correlation potential and
the screening of interaction between valence electrons by the core electrons
) may be calculated with all
valence electrons removed. This allows one to avoid subtraction diagrams
which make accurate inclusion of the core-valence correlations for
prohibitively complicated. Then the CI Hamiltonian for valence electrons is
calculated using orbitals in complete potential (the mean field
produced by all electrons); + are added to the CI
Hamiltonian to account for the core-valence correlations. We calculate
and using many-body perturbation theory in which
dominating classes of diagrams are included in all orders.
We use neutral Xe I and all positive ions up to Xe VIII as a testing ground.
We found that the core electron density for all these systems is practically
the same. Therefore, we use the same and to build
the CI Hamiltonian in all these systems (). Good agreement
with experiment for energy levels and Land\'{e} factors is demonstrated for all
cases from Xe I to Xe VIII.Comment: 13 pages, 5 figure
Micromagic clock: microwave clock based on atoms in an engineered optical lattice
We propose a new class of atomic microwave clocks based on the hyperfine
transitions in the ground state of aluminum or gallium atoms trapped in optical
lattices. For these elements magic wavelengths exist at which both levels of
the hyperfine doublet are shifted at the same rate by the lattice laser field,
cancelling its effect on the clock transition. Our analysis of various
systematic effects shows that, while offering an improved control over
systematic errors, the accuracy of the proposed microwave clock is competitive
to that of the state-of-the-art primary frequency standard.Comment: 4pgs+3fig
AC Stark shift of the Cs microwave atomic clock transitions
We analyze the AC Stark shift of the Cs microwave atomic clock transition
theoretically and experimentally. Theoretical and experimental data are in a
good agreement with each other. Results indicate the absence of a magic
wavelength at which there would be no differential shift of the clock states
having zero projections of the total angular momentum