1,495,820 research outputs found
Reply on the comment on the paper "Superconducting transition in Nb nanowires fabricated using focused ion beam"
In this communication we present our response to the recent comment of A.
Engel regarding our paper on FIB- fabricated Nb nanowires (see Vol. 20 (2009)
Pag. 465302). After further analysis and additional experimental evidence, we
conclude that our interpretation of the experimental results in light of QPS
theory is still valid when compared with the alternative proximity-based model
as proposed by A. Engel.Comment: 3 pages, 1 figure, accepted by Nanotechnolog
Strain-Induced Coupling of Spin Current to Nanomechanical Oscillations
We propose a setup which allows to couple the electron spin degree of freedom
to the mechanical motions of a nanomechanical system not involving any of the
ferromagnetic components. The proposed method employs the strain induced
spin-orbit interaction of electrons in narrow gap semiconductors. We have shown
how this method can be used for detection and manipulation of the spin flow
through a suspended rod in a nanomechanical device.Comment: 4 pages, 1 figur
VLA observations of a sample of galaxies with high far-infrared luminosities
Preliminary results are presented from a radio survey of galaxies detected by the IRAS minisurvey. It was found that the main difference between galaxies selected in the far infrared and those selected in the optical is that the former have higher radio luminosities and that the radio emission is more centrally concentrated. There is some evidence that the strong central radio sources in the galaxies selected in the infrared are due to star formation, the star formation rate divided by the volume in which the star formation is occuring is 100 to 1000 times greater in the galaxies selected in the infrared than in the disks of normal galaxies
Green's and spectral functions of the small Frolich polaron
According to recent Quantum Monte Carlo simulations the small polaron theory
is practically exact in a wide range of the long-range (Frohlich)
electron-phonon coupling and adiabatic ratio. We apply the Lang-Firsov
transformation to convert the strong-coupling term in the Hamiltonian into the
form of an effective hopping integral and derive the single-particle Green's
function describing propagation of the small Frohlich polaron. One and two
dimensional spectral functions are studied by expanding the Green's function
perturbatively. Numerical calculations of the spectral functions are produced.
Remarkably, the coherent spectral weight (Z) and effective mass (Z')
renormalisation exponents are found to be different with Z'>>Z, which can
explain a small coherent spectral weight and a relatively moderate mass
enhancement in oxides.Comment: RevTeX, 5 pages, 2 postscript figures, LaTeX processing problems
correcte
Universality in the Gravitational Stretching of Clocks, Waves and Quantum States
There are discernible and fundamental differences between clocks, waves and
physical states in classical physics. These fundamental concepts find a common
expression in the context of quantum physics in gravitational fields; matter
and light waves, quantum states and oscillator clocks become quantum synonymous
through the Planck-Einstein-de Broglie relations and the equivalence principle.
With this insight, gravitational effects on quantum systems can be simply and
accurately analyzed. Apart from providing a transparent framework for
conceptual and quantitative thinking on matter waves and quantum states in a
gravitational field, we address and resolve with clarity the recent
controversial discussions on the important issue of the relation and the
crucial difference between gravimetery using atom interferometers and the
measurement of gravitational time dilation.Comment: Gravity Research Foundation honorable mention, 201
Signatures of supernova neutrino oscillations in the Earth mantle and core
The Earth matter effects on supernova (SN) neutrinos can be identified at a
single detector through peaks in the Fourier transform of their ``inverse
energy'' spectrum. The positions of these peaks are independent of the SN
models and therefore the peaks can be used as a robust signature of the Earth
matter effects, which in turn can distinguish between different neutrino mixing
scenarios. Whereas only one genuine peak is observable when the neutrinos
traverse only the Earth mantle, traversing also the core gives rise to multiple
peaks. We calculate the strengths and positions of these peaks analytically and
explore their features at a large scintillation detector as well as at a
megaton water Cherenkov detector through Monte Carlo simulations. We propose a
simple algorithm to identify the peaks in the actual data and quantify the
chances of a peak identification as a function of the location of the SN in the
sky.Comment: 17 pages, 9 figure
Perturbative and instanton corrections to the OPE of CPOs in N=4 SYM_4
We study perturbative and instanton corrections to the Operator Product
Expansion of the lowest weight Chiral Primary Operators of N=4 SYM_4. We
confirm the recently observed non-renormalization of various operators (notably
of the double-trace operator with dimension 4 in the 20 irrep of SU(4)), that
appear to be unprotected by unitarity restrictions. We demonstrate the
splitting of the free-field theory stress tensor and R-symmetry current in
supermultiplets acquiring different anomalous dimensions in perturbation theory
and argue that certain double-trace operators also undergo a perturbative
splitting into operators dual to string and two-particle gravity states
respectively. The instanton contributions affect only those double-trace
operators that acquire finite anomalous dimensions at strong coupling. For the
leading operators of this kind, we show that the ratio of their anomalous
dimensions at strong coupling to the anomalous dimensions due to instantons is
the same number.Comment: Latex, 26p, typos are removed, a strong-coupling anomalous dimension
of one of the double-trace operators is correcte
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