2,319 research outputs found
Universality of the edge tunneling exponent of fractional quantum Hall liquids
Recent calculations of the edge tunneling exponents in quantum Hall states
appear to contradict their topological nature. We revisit this issue and find
no fundamental discrepancies. In a microscopic model of fractional quantum Hall
liquids with electron-electron interaction and confinement, we calculate the
edge Green's function via exact diagonalization. Our results for
and 2/3 suggest that in the presence of Coulomb interaction, the sharpness of
the edge and the strength of the edge confining potential, which can lead to
edge reconstruction, are the parameters that are relevant to the universality
of the electron tunneling I-V exponent.Comment: 5 pages, 3 figure
The IDEAL (Integrated Design and Engineering Analysis Languages) modeling methodology: Capabilities and Applications
The IDEAL (Integrated Design and Engineering Analysis Languages) modeling methodology has been formulated and applied over a five-year period. It has proven to be a unique, integrated approach utilizing a top-down, structured technique to define and document the system of interest; a knowledge engineering technique to collect and organize system descriptive information; a rapid prototyping technique to perform preliminary system performance analysis; and a sophisticated simulation technique to perform in-depth system performance analysis
IDEAL: A methology for developing information systems
As a result of improved capabilities obtained through current computer technologies, application programs and expert systems, Enterprises are being designed or upgraded to be highly integrated and automated information systems. To design or modify Enterprises, it is necessary to first define what functions are to be performed within the Enterprise, identify which functions are potential candidates for automation, and what automated or expert systems are available, or must be developed, to accomplish the selected function. Second, it is necessary to define and analyze the informational requirements for each function along with the informational relationships among the functions so that a database structure can be established to support the Enterprise. To perform this type of system design, an integrated set of analysis tools is required to support the information analysis process. The IDEAL (Integrated Design and Engineering Analysis Languages) methodology provides this integrated set of tools and is discussed
Strong-field spatial interference in a tailored electromagnetic bath
Light scattered by a regular structure of atoms can exhibit interference
signatures, similar to the classical double-slit. These first-order
interferences, however, vanish for strong light intensities, restricting
potential applications. Here, we show how to overcome these limitations to
quantum interference in strong fields. First, we recover the first-order
interference in strong fields via a tailored electromagnetic bath with a
suitable frequency dependence. At strong driving, the optical properties for
different spectral bands are distinct, thus extending the set of observables.
We further show that for a two-photon detector as, e.g., in lithography,
increasing the field intensity leads to twice the spatial resolution of the
second-order interference pattern compared to the weak-field case.Comment: final versio
Multifractality of wavefunctions at the quantum Hall transition revisited
We investigate numerically the statistics of wavefunction amplitudes
at the integer quantum Hall transition. It is demonstrated that
in the limit of a large system size the distribution function of is
log-normal, so that the multifractal spectrum is exactly parabolic.
Our findings lend strong support to a recent conjecture for a critical theory
of the quantum Hall transition.Comment: 4 pages Late
Dimensionality dependence of the wave function statistics at the Anderson transition
The statistics of critical wave functions at the Anderson transition in three
and four dimensions are studied numerically. The distribution of the inverse
participation ratios (IPR) is shown to acquire a scale-invariant form in
the limit of large system size. Multifractality spectra governing the scaling
of the ensemble-averaged IPRs are determined. Conjectures concerning the IPR
statistics and the multifractality at the Anderson transition in a high spatial
dimensionality are formulated.Comment: 4 pages, 4 figure
Quantum superposition principle and generation of ultrashort optical pulses
We discuss the propagation of laser radiation through a medium of quantum
prepared {\Lambda}-type atoms in order to enhance the insight into the physics
of QS-PT generator suggested in Phys. Rev. A 80, 035801 (2009). We obtain
analytical results which give a qualitatively corerct description of the
outcoming series of ultrashort optical pulses and show that for the case of
alkali vapor medium QS-PT generation may be implemented under ordinary
experimental conditions
Isomer triggering via nuclear excitation by electron capture
Triggering of long-lived nuclear isomeric states via coupling to the atomic
shells in the process of nuclear excitation by electron capture (NEEC) is
studied. NEEC occurring in highly-charged ions can excite the isomeric state to
a triggering level that subsequently decays to the ground state. We present
total cross sections for NEEC isomer triggering considering experimentally
confirmed low-lying triggering levels and reaction rates based on realistic
experimental parameters in ion storage rings. A comparison with other isomer
triggering mechanisms shows that, among these, NEEC is the most efficient.Comment: minor changes - updated to the final version; 4 pages, 1 figur
Multifractality at the spin quantum Hall transition
Statistical properties of critical wave functions at the spin quantum Hall
transition are studied both numerically and analytically (via mapping onto the
classical percolation). It is shown that the index characterizing the
decay of wave function correlations is equal to 1/4, at variance with the
decay of the diffusion propagator. The multifractality spectra of
eigenfunctions and of two-point conductances are found to be
close-to-parabolic, and .Comment: 4 pages, 3 figure
Novel insights into transfer processes in the reaction 16O+208Pb at sub-barrier energies
The collision of the doubly-magic nuclei O+Pb is a benchmark
in nuclear reaction studies. Our new measurements of back-scattered
projectile-like fragments at sub-barrier energies show show that transfer of 2
protons () is much more probable than -particle transfer.
transfer probabilities are strongly enhanced compared to expectations for the
sequential transfer of two uncorrelated protons; at energies around the fusion
barrier absolute probabilities for two proton transfer are similar to those for
one proton transfer. This strong enhancement indicates strong pairing
correlations in O, and suggests evidence for the occurrence of a nuclear
supercurrent of two-proton Cooper pairs in this reaction, already at energies
well below the fusion barrier.Comment: 5 pages, 3 figure
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