33,734 research outputs found
Fault-tolerant linear optics quantum computation by error-detecting quantum state transfer
A scheme for linear optical implementation of fault-tolerant quantum
computation is proposed, which is based on an error-detecting code. Each
computational step is mediated by transfer of quantum information into an
ancilla system embedding error-detection capability. Photons are assumed to be
subjected to both photon loss and depolarization, and the threshold region of
their strengths for scalable quantum computation is obtained, together with the
amount of physical resources consumed. Compared to currently known results, the
present scheme reduces the resource requirement, while yielding a comparable
threshold region.Comment: 9 pages, 7 figure
Dilaton as a Dark Matter Candidate and its Detection
Assuming that the dilaton is the dark matter of the universe, we propose an
experiment to detect the relic dilaton using the electromagnetic resonant
cavity, based on the dilaton-photon conversion in strong electromagnetic
background. We calculate the density of the relic dilaton, and estimate the
dilaton mass for which the dilaton becomes the dark matter of the universe.
With this we calculate the dilaton detection power in the resonant cavity, and
compare it with the axion detection power in similar resonant cavity
experiment.Comment: 23 pages, 2 figure
Finite-size scaling theory for explosive percolation transitions
The finite-size scaling (FSS) theory for continuous phase transitions has
been useful in determining the critical behavior from the size dependent
behaviors of thermodynamic quantities. When the phase transition is
discontinuous, however, FSS approach has not been well established yet. Here,
we develop a FSS theory for the explosive percolation transition arising in the
Erd\H{o}s and R\'enyi model under the Achlioptas process. A scaling function is
derived based on the observed fact that the derivative of the curve of the
order parameter at the critical point diverges with system size in a
power-law manner, which is different from the conventional one based on the
divergence of the correlation length at . We show that the susceptibility
is also described in the same scaling form. Numerical simulation data for
different system sizes are well collapsed on the respective scaling functions.Comment: 5 pages, 5 figure
EFFECTS OF THE CANADIAN WHEAT BOARD ON THE U.S. WHEAT INDUSTRY
The practices of the Canadian Wheat Board (CWB) are an important issue in U.S. - Canada trade disputes and WTO negotiations. This study analyzes the CWB?s effect on U.S. producers by reviewing findings from previous research and developing models to analyze CWB wheat exports to the United States and the competitive structure of Canadian wheat exports in the world market. U.S. grain producers could benefit from the removal of the CWB as the United States could become more competitive in export markets. However, elimination of the CWB could also result in an increase in Canadian wheat exports to the United States as Canadian producers near the border could sell directly to the United States to take advantage of market opportunities. The net effect is difficult to quantify. The net benefits may be significant in the short run, but reduced significantly in the long run. Similarly, if Canada reforms its wheat board by eliminating trade-distorting subsidies, the United States may increase its exports and Canadian exports to the United States may increase. The net benefits from reforming the CWB could be greater than those from eliminating it. However, the United States could benefit the most from complete elimination of state trading enterprises (STEs), since they have elements distorting trade flows and the United States competes with several STEs in the world wheat market.Canadian Wheat Board, state trading enterprises, price discrimination, wheat exports, Crop Production/Industries, International Relations/Trade,
Phenomenological Theory of Superconductivity and Magnetism in HoDyNiBC
The coexistence of the superconductivity and magnetism in the
HoDyNiBC is studied by using Ginzburg-Landau theory. This
alloy shows the coexistence and complex interplay of superconducting and
magnetic order. We propose a phenomenological model which includes two magnetic
and two superconducting order parameters accounting for the multi-band
structure of this material. We describe phenomenologically the magnetic
fluctuations and order and demonstrate that they lead to anomalous behavior of
the upper critical field. The doping dependence of in
HoDyNiBC showing a reentrance behavior are analyzed
yielding a very good agreement with experimental data.Comment: 4 pages, 3 figures, REVTeX, submitted to PR
Color Reflection Invariance and Monopole Condensation in QCD
We review the quantum instability of the Savvidy-Nielsen-Olesen (SNO) vacuum
of the one-loop effective action of SU(2) QCD, and point out a critical defect
in the calculation of the functional determinant of the gluon loop in the SNO
effective action. We prove that the gauge invariance, in particular the color
reflection invariance, exclude the unstable tachyonic modes from the gluon loop
integral. This guarantees the stability of the magnetic condensation in QCD.Comment: 28 pages, 3 figures, JHEP styl
Lamm, Valluri, Jentschura and Weniger comment on "A Convergent Series for the QED Effective Action" by Cho and Pak [Phys. Rev. Lett. vol. 86, pp. 1947-1950 (2001)]
Complete results were obtained by us in [Can. J. Phys. 71, 389 (1993)] for
convergent series representations of both the real and the imaginary part of
the QED effective action; these derivations were based on correct intermediate
steps. In this comment, we argue that the physical significance of the
"logarithmic correction term" found by Cho and Pak in [Phys. Rev. Lett. 86,
1947 (2001)] in comparison to the usual expression for the QED effective action
remains to be demonstrated. Further information on related subjects can be
found in Appendix A of hep-ph/0308223 and in hep-th/0210240.Comment: 1 page, RevTeX; only "meta-data" update
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