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Magic Wavelengths for Terahertz Clock Transitions
Magic wavelengths for laser trapping of boson isotopes of alkaline-earth Sr,
Ca and Mg atoms are investigated while considering terahertz clock transitions
between the metastable triplet states. Our
calculation shows that magic wavelengths of trapping laser do exist. This
result is important because those metastable states have already been used to
realize accurate clocks in the terahertz frequency domain. Detailed discussions
for magic wavelength for terahertz clock transitions are given in this paper.Comment: 7 page
Continuous Charge Modulated Diagonal Phase in Manganites
We present a novel ground state that explain the continuous modulated charge
diagonal order recently observed in manganese oxides, at hole densities
larger than one half. In this diagonal phase the charge is modulated with a
predominant Fourier component inversely proportional to . Magnetically
this state consist of antiferromagnetic coupled zig-zag chains. For a wide
range of relevant physical parameters as electron-phonon coupling,
antiferromagnetic interaction between Mn ions and on-site Coulomb repulsion,
the diagonal phase is the ground state of the system. The diagonal phase is
favored by the modulation of the hopping amplitude along the zig-zag chains,
and it is stabilized with respect to the one dimensional straight chain by the
electron phonon coupling. For realistic estimation of the physical parameters,
the diagonal modulation of the electron density is only a small fraction of the
average charge, a modulation much smaller than the obtained by distributing
Mn and Mn ions. We discuss also the spin and orbital structure
properties of this new diagonal phase.Comment: 4 pages, 4 figures include
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