150 research outputs found
Deceleration of continuous molecular beams
A method for decelerating a continuous beam of neutral polar molecules is
theoretically demonstrated. This method utilizes non-uniform, static electric
fields and regions of adiabatic population transfer to generate a mechanical
force that opposes the molecular beam's velocity. By coupling this technique
with dissipative trap-loading, molecular densities cm are
possible. When used in combination with forced evaporative cooling the proposed
method may represent a viable route to quantum degeneracy for a wide-class of
molecular species
Discontinuity of the chemical potential in RDMFT for open-shell systems
We employ reduced density-matrix functional theory in the calculation of the
fundamental gap of open-shell systems. The formula for the calculation of the
fundamental gap is derived with special attention to the spin of the neutral
and the charged systems. We discuss the effects of different functionals as
well as the changes due to different basis sets. Also, we investigate the
importance of varying the natural orbitals for the calculation of the
fundamental gapComment: 9 pages, 6 figures, submitted to Phys. Rev.
О НЕОБХОДИМЫХ РЕФОРМАХ В ТОВАРНОМ ДВИЖЕНИИ
Archival publication from the journal «Railway Business», 1900.Архивная публикация из журнала «Железнодорожное дело», 1900 г. Железнодорожное дело. – 1900. – № 26. – С. 273–275. Из фондов библиотеки МИИТ
Electric dipole moment enhancement factor of thallium
The goal of this work is to resolve the present controversy in the value of
the EDM enhancement factor of Tl. We have carried out several calculations by
different high-precision methods, studied previously omitted corrections, as
well as tested our methodology on other parity conserving quantities. We find
the EDM enhancement factor of Tl to be equal to -573(20). This value is 20%
larger than the recently published result of Nataraj et al. [Phys. Rev. Lett.
106, 200403 (2011)], but agrees very well with several earlier results.Comment: 5 pages; v2: link to supplemental material adde
Confinement resonances in photoionization of endohedral atoms: a myth or reality?
We demonstrate that the structure of confinement resonances in the
photoionization cross section of an endohedral atom is very sensitive to the
mean displacement of the atom from the cage center. The resonances are
strongly suppressed if 2 exceeds the photoelectron half-wavelength. We
explain the results of recent experiments which contradict the earlier
theoretical predictions on the existence of confinement resonances in
particular endohedral systems.Comment: 4 pages, 5 figures, RevTe
Predicting scattering properties of ultracold atoms: adiabatic accumulated phase method and mass scaling
Ultracold atoms are increasingly used for high precision experiments that can
be utilized to extract accurate scattering properties. This calls for a
stronger need to improve on the accuracy of interatomic potentials, and in
particular the usually rather inaccurate inner-range potentials. A boundary
condition for this inner range can be conveniently given via the accumulated
phase method. However, in this approach one should satisfy two conditions,
which are in principle conflicting, and the validity of these approximations
comes under stress when higher precision is required. We show that a better
compromise between the two is possible by allowing for an adiabatic change of
the hyperfine mixing of singlet and triplet states for interatomic distances
smaller than the separation radius. A mass scaling approach to relate
accumulated phase parameters in a combined analysis of isotopically related
atom pairs is described in detail and its accuracy is estimated, taking into
account both Born-Oppenheimer and WKB breakdown. We demonstrate how numbers of
singlet and triplet bound states follow from the mass scaling.Comment: 14 pages, 9 figure
Effects of Coulomb interactions on the splitting of luminescence lines
We study the splitting between the right-hand and left-hand circularly
polarized luminescence lines in a quantum dot under relatively weak confinement
regime and resonant high-power excitation. When the dot is populated with an
even number of electron-hole pairs (biexciton and higher excitations), the
splitting measures basically the Zeeman energy. However, in the odd number of
pairs case, we have, in addition to the Zeeman and Overhauser shifts, a
contribution to the splitting coming from Coulomb interactions. This
contribution is of the order of a few meV, and shows distinct signatures of
shell-filling in the quantum dot.Comment: Submitted for publicatio
Precision study of 6p 2Pj - 8s 2S1/2 relative transition matrix elements in atomic Cs
A combined experimental and theoretical study of transition matrix elements
of the 6p 2Pj - 8s 2S1/2 transition in atomic Cs is reported. Measurements of
the polarization-dependent two-photon excitation spectrum associated with the
transition were made in an approximately 200 cm-1 range on the low frequency
side of the 6s 2S1/2 - 6p 2P3/2 resonance. The measurements depend
parametrically on the relative transition matrix elements, but also are
sensitive to far-off-resonance 6s 2S1/2 - np 2Pj - 8s 2S1/2 transitions. In the
past, this dependence has yielded a generalized sum rule, the value of which is
dependent on sums of relative two-photon transition matrix elements. In the
present case, best available determinations from other experiments are combined
with theoretical matrix elements to extract the ratio of transition matrix
elements for the 6p 2Pj - 8s 2S1/2 (j = 1/2,3/2) transition. The resulting
experimental value of 1.423(2) is in excellent agreement with the theoretical
value, calculated using a relativistic all-order method, of 1.425(2)
The X and a states of LiCs studied by Fourier-transform spectroscopy
We present the first high-resolution spectroscopic study of LiCs. LiCs is
formed in a heat pipe oven and studied via laser-induced fluorescence
Fourier-transform spectroscopy. By exciting molecules through the
X-B and X-D transitions vibrational
levels of the X ground state have been observed up to 3cm^{-1}
below the dissociation limit enabling an accurate construction of the
potential. Furthermore, rovibrational levels in the a triplet
ground state have been observed because the excited states obtain sufficient
triplet character at the corresponding excited atomic asymptote. With the help
of coupled channels calculations accurate singlet and triplet ground state
potentials were derived reaching the atomic ground state asymptote and allowing
first predictions of cold collision properties of Li + Cs pairs.Comment: 10 pages, 5 figures. Submitted for publicatio
Quantum Theory of High Harmonic Generation via Above Threshold Ionization and Stimulated Recombination
Fully quantum treatment explicitly presents the high harmonic generation as a
three-stage process: above threshold ionization (ATI) is followed by the
continuum electron propagation in a laser field and subsequent stimulated
recombination back into the initial state. The contributions of all ATI
channels add up coherently. All three stages of the process are described by
simple, mostly analytical expressions. A very good quantitative agreement with
the previous calculations on the harmonic generation by H ion is
demonstrated, thus supplementing the conceptual significance of the theory with
its practical efficiency.Comment: Latex IOP stile, plus 1 figure in a PostScript fil
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