11,280 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
Compact Toroidal Ion Trap Design and Optimization
We present the design of a new type of compact toroidal, or "halo", ion trap.
Such traps may be useful for mass spectrometry, studying small Coulomb cluster
rings, quantum information applications, or other quantum simulations where a
ring topology is of interest. We present results from a Monte Carlo
optimization of the trap design parameters using finite-element analysis
simulations that minimizes higher-order anharmonic terms in the trapping
pseudopotential, while maintaining complete control over ion placement at the
pseudopotential node in 3D using static bias fields. These simulations are
based on a practical electrode design using readily-available parts, yet can be
easily scaled to any size trap with similar electrode spacings. We also derive
the conditions for a crystal phase transition for two ions in the compact halo
trap, the first non-trivial phase transition for Coulomb crystals in this
geometry.Comment: 8 pages, 9 figure
High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysis
We present a generic approach for treating the effect of nuclear motion in
the high-order harmonic generation from polyatomic molecules. Our procedure
relies on a separation of nuclear and electron dynamics where we account for
the electronic part using the Lewenstein model and nuclear motion enters as a
nuclear correlation function. We express the nuclear correlation function in
terms of Franck-Condon factors which allows us to decompose nuclear motion into
modes and identify the modes that are dominant in the high-order harmonic
generation process. We show results for the isotopes CH and CD and
thereby provide direct theoretical support for a recent experiment [Baker {\it
et al.}, Science {\bf 312}, 424 (2006)] that uses high-order harmonic
generation to probe the ultra-fast structural nuclear rearrangement of ionized
methane.Comment: 6 pages, 6 figure
Colour-singlet strangelets at finite temperature
Considering massless and quarks, and massive (150 MeV) quarks in
a bag with the bag pressure constant MeV, a colour-singlet
grand canonical partition function is constructed for temperatures
MeV. Then the stability of finite size strangelets is studied minimizing the
free energy as a function of the radius of the bag. The colour-singlet
restriction has several profound effects when compared to colour unprojected
case: (1) Now bulk energy per baryon is increased by about MeV making the
strange quark matter unbound. (2) The shell structures are more pronounced
(deeper). (3) Positions of the shell closure are shifted to lower -values,
the first deepest one occuring at , famous -particle ! (4) The shell
structure at vanishes only at MeV, though for higher
-values it happens so at MeV.Comment: Revtex file(8 pages)+6 figures(ps files) available on request from
first Autho
Experimental Bell Inequality Violation with an Atom and a Photon
We report the measurement of a Bell inequality violation with a single atom
and a single photon prepared in a probabilistic entangled state. This is the
first demonstration of such a violation with particles of different species.
The entanglement characterization of this hybrid system may also be useful in
quantum information applications.Comment: 4 pages, 2 figure
Influence of water temperature on the efficacy of diquat and endothall versus curlyleaf pondweed
determine the impact of water temperature on the efficacy
of the contact herbicides diquat (6,7-dihydrodipyrido [1,2-
α:2’,1’-c] pyrazinediium ion) and endothall (7-oxabicyclo
[2.2.1] heptane-2,3-dicarboxylic acid) for control of the exotic
nuisance species curlyleaf pondweed (Potamogeton crispus L.)
across a range of water temperatures
Magnetoresistence engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates
We present magnetoresistance (MR) experiments on an InAs nanowire quantum dot
device with two ferromagnetic sidegates (FSGs) in a split-gate geometry. The
wire segment can be electrically tuned to a single dot or to a double dot
regime using the FSGs and a backgate. In both regimes we find a strong MR and a
sharp MR switching of up to 25\% at the field at which the magnetizations of
the FSGs are inverted by the external field. The sign and amplitude of the MR
and the MR switching can both be tuned electrically by the FSGs. In a double
dot regime close to pinch-off we find {\it two} sharp transitions in the
conductance, reminiscent of tunneling MR (TMR) between two ferromagnetic
contacts, with one transition near zero and one at the FSG switching fields.
These surprisingly rich characteristics we explain in several simple resonant
tunneling models. For example, the TMR-like MR can be understood as a
stray-field controlled transition between singlet and a triplet double dot
states. Such local magnetic fields are the key elements in various proposals to
engineer novel states of matter and may be used for testing electron spin-based
Bell inequalities.Comment: 7 pages, 6 figure
Planar Ion Trap Geometry for Microfabrication
We describe a novel high aspect ratio radiofrequency linear ion trap geometry
that is amenable to modern microfabrication techniques. The ion trap electrode
structure consists of a pair of stacked conducting cantilevers resulting in
confining fields that take the form of fringe fields from parallel plate
capacitors. The confining potentials are modeled both analytically and
numerically. This ion trap geometry may form the basis for large scale quantum
computers or parallel quadrupole mass spectrometers.
PACS: 39.25.+k, 03.67.Lx, 07.75.+h, 07.10+CmComment: 14 pages, 16 figure
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