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42

Sep 19, 2013
09/13

by
Andy T. S. Wan; M. H. S. Amin; Shannon X. Wang

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We study the effect of an environment consisting of noninteracting two level systems on Landau-Zener transitions with an interest on the performance of an adiabatic quantum computer. We show that if the environment is initially at zero temperature, it does not affect the transition probability. An excited environment, however, will always increase the probability of making a transition out of the ground state. For the case of equal intermediate gaps, we find an analytical upper bound for the...

Source: http://arxiv.org/abs/cond-mat/0703085v3

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83

Sep 23, 2013
09/13

by
Frédéric Klopp; Shu Nakamura

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We study Lifshitz tails for random Schr\"odinger operators where the random potential is alloy type in the sense that the single site potentials are independent, identically distributed, but they may have various function forms. We suppose the single site potentials are distributed in a finite set of functions, and we show that under suitable symmetry conditions, they have Lifshitz tail at the bottom of the spectrum except for special cases. When the single site potential is symmetric with...

Source: http://arxiv.org/abs/0903.2105v2

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32

Sep 23, 2013
09/13

by
D. B. Melrose; M. Z. Rafat; Q. Luo

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We consider the motion of a charge in a large amplitude electrostatic wave with a triangular wave form relevant to an oscillating model of a pulsar magnetosphere. The (one-dimensional) orbit of a particle in such a wave is found exactly in terms of Weierstrass functions. The result is used to discuss linear acceleration emission (at both low and high frequencies) in an oscillating model for pulsars. An explicit expression for the emissivity is derived in an accompanying paper (Melrose & Luo...

Source: http://arxiv.org/abs/0903.2877v1

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22

Sep 21, 2013
09/13

by
Fabio Riccioni; Peter West

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We give a method of deriving the field-strengths of all massless and massive maximal supergravity theories in any dimension starting from the Kac-Moody algebra $E_{11}$. Considering the subalgebra of $E_{11}$ that acts on the fields in the non-linear realisation as a global symmetry, we show how this is promoted to a gauge symmetry enlarging the algebra by the inclusion of additional generators. We show how this works in eleven dimensions, and we call the resulting enlarged algebra...

Source: http://arxiv.org/abs/0902.4678v2

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31

Sep 19, 2013
09/13

by
Bas Spitters

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Locatedness is one of the fundamental notions in constructive mathematics. The existence of a positivity predicate on a locale, i.e. the locale being overt, or open, has proved to be fundamental in constructive locale theory. We show that the two notions are intimately connected. Bishop defines a metric space to be compact if it is complete and totally bounded. A subset of a totally bounded set is again totally bounded iff it is located. So a closed subset of a Bishop compact set is Bishop...

Source: http://arxiv.org/abs/math/0703561v2

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50

Sep 21, 2013
09/13

by
Stephan Durr

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A Lie-algebra based recipe for smoothing gauge links in lattice field theory is presented, building on the matrix logarithm. With or without hypercubic nesting, this LOG/HYL smearing yields fat links which are differentiable w.r.t. the original ones. This is essential for defining UV-filtered ("fat link") fermion actions which may be simulated with a HMC-type algorithm. The effect of this smearing on the distribution of plaquettes and on the residual mass of tree-level O(a)-improved...

Source: http://arxiv.org/abs/0709.4110v2