16,116 research outputs found
High-harmonic generation from arbitrarily oriented diatomic molecules including nuclear motion and field-free alignment
We present a theoretical model of high-harmonic generation from diatomic
molecules. The theory includes effects of alignment as well as nuclear motion
and is used to predict results for N, O, H and D. The results
show that the alignment dependence of high-harmonics is governed by the
symmetry of the highest occupied molecular orbital and that the inclusion of
the nuclear motion in the theoretical description generally reduces the
intensity of the harmonic radiation. We compare our model with experimental
results on N and O, and obtain very good agreement.Comment: 12 pages, 8 figures, 2 tables; legends revised on Figs. 1,3,4,6 and
Spin squeezing and precision probing with light and samples of atoms in the gaussian approximation
We consider an ensemble of trapped atoms interacting with a continuous wave
laser field. For sufficiently polarized atoms and for a polarized light field,
we may approximate the non-classical components of the collective spin angular
momentum operator for the atoms and the Stokes vectors of the field by
effective position and momentum variables for which we assume a gaussian state.
Within this approximation, we present a theory for the squeezing of the atomic
spin by polarization rotation measurements on the probe light. We derive
analytical expressions for the squeezing with and without inclusion of the
noise effects introduced by atomic decay and by photon absorption. The theory
is readily adapted to the case of inhomogeneous light-atom coupling [A. Kuzmich
and T.A.B. Kennedy, Phys. Rev. Lett. Vol. 92, 030407 (2004)]. As a special
case, we show how to formulate the theory for an optically thick sample by
slicing the gas into pieces each having only small photon absorption
probability. Our analysis of a realistic probing and measurement scheme shows
that it is the maximally squeezed component of the atomic gas that determines
the accuracy of the measurement.Comment: 12 pages, 5 figure
High Q Cavity Induced Fluxon Bunching in Inductively Coupled Josephson Junctions
We consider fluxon dynamics in a stack of inductively coupled long Josephson
junctions connected capacitively to a common resonant cavity at one of the
boundaries. We study, through theoretical and numerical analysis, the
possibility for the cavity to induce a transition from the energetically
favored state of spatially separated shuttling fluxons in the different
junctions to a high velocity, high energy state of identical fluxon modes.Comment: 8 pages, 5 figure
Classification of String-like Solutions in Dilaton Gravity
The static string-like solutions of the Abelian Higgs model coupled to
dilaton gravity are analyzed and compared to the non-dilatonic case. Except for
a special coupling between the Higgs Lagrangian and the dilaton, the solutions
are flux tubes that generate a non-asymptotically flat geometry. Any point in
parameter space corresponds to two branches of solutions with two different
asymptotic behaviors. Unlike the non-dilatonic case, where one branch is always
asymptotically conic, in the present case the asymptotic behavior changes
continuously along each branch.Comment: 15 pages, 6 figures. To be published in Phys. Rev.
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