10,673 research outputs found
Toric partial density functions and stability of toric varieties
Let denote a polarized toric K\"ahler manifold. Fix a
toric submanifold and denote by the
partial density function corresponding to the partial Bergman kernel projecting
smooth sections of onto holomorphic sections of that vanish to
order at least along , for fixed such that . We
prove the existence of a distributional expansion of as , including the identification of the coefficient of as a
distribution on . This expansion is used to give a direct proof that if
has constant scalar curvature, then must be slope semi-stable
with respect to . Similar results are also obtained for more general partial
density functions. These results have analogous applications to the study of
toric K-stability of toric varieties.Comment: Accepted by Mathematische Annalen on 13 September 201
Measurement of absolute transition frequencies of 87Rb to nS and nD Rydberg states by means of electromagnetically induced transparency
We report the measurement of absolute excitation frequencies of 87Rb to nS
and nD Rydberg states. The Rydberg transition frequencies are obtained by
observing electromagnetically induced transparency on a rubidium vapor cell.
The accuracy of the measurement of each state is < 1 MHz, which is achieved by
frequency stabilizing the two diode lasers employed for the spectroscopy to a
frequency comb and a frequency comb calibrated wavelength meter, respectively.
Based on the spectroscopic data we determine the quantum defects of 87Rb, and
compare it with previous measurements on 85Rb. We determine the ionization
frequency from the 5S1/2(F=1) ground state of 87Rb to 1010.0291646(3) THz,
providing the binding energy of the ground state with an accuracy improved by
two orders of magnitude
An observable entanglement measure for unknown mixed quantum states
We show how an unknown mixed quantum state's entanglement can be quantified
by a suitable, local parity measurement on its two-fold copy.Comment: in press in PR
Next to leading order evolution of SIDIS processes in the forward region
We compute the order quark initiated corrections to
semi-inclusive deep inelastic scattering extending the approach developed
recently for the gluon contributions. With these corrections we complete the
order QCD description of these processes, verifying explicitly the
factorization of collinear singularities. We also obtain the corresponding NLO
evolution kernels, relevant for the scale dependence of fracture functions. We
compare the non-homogeneous evolution effects driven by these kernels with
those obtained at leading order accuracy and discuss their phenomenological
implications.Comment: 18 pages, 4 ps figures, uses revtex4 and feynmf. Accepted for
publication in Nuclear Physics
Transport through a quantum dot with excitonic dot-lead coupling
We study the effect of a dot-lead interaction on transport through a quantum
dot hybridized to two semi-infinite Luttinger-liquid leads. A bosonization
approach is applied to treat the interaction between charge fluctuations on the
dot and the dynamically generated image charge in the leads. The nonequilibrium
distribution function of the dot and the tunneling current are computed within
a master-equation approach. The presence of the excitonic dot-lead coupling is
found to enhance transport in the vicinity of the Coulomb-blockade threshold.
This behavior is in contrast to the usual power-law suppression of electronic
tunneling which is found if this interaction is ignored.Comment: 9 pages, 2 figure
Polarization singularities from unfolding an optical vortex through a birefringent crystal
Optical vortices (nodal lines and phase singularities) are the generic singularities of scalar optics but are unstable in vector optics. We investigate experimentally and theoretically the unfolding of a uniformly polarized optical vortex beam on propagation through a birefringent crystal and characterize the output field in terms of polarization singularities (C lines and points of circular polarization; L surfaces and lines of linear polarization). The field is described both in the 2-dimensional transverse plane, and in three dimensions, where the third is abstract, representing an optical path length propagated through the crystal. Many phenomena of singular optics, such as topological charge conservation and singularity reconnections, occur naturally in the description
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