9,110 research outputs found
Waiting time distribution for trains of quantized electron pulses
We consider a sequence of quantized Lorentzian pulses of non-interacting
electrons impinging on a quantum point contact (QPC) and study the waiting time
distribution (WTD), for any transmission and any number of pulses. As the
degree of overlap between the electronic wave functions is tuned, the WTD
reveals how the correlations between particles are modified. In the weak
overlap regime, the WTD is made of several equidistant peaks, separated by the
same period as the incoming pulses, contained in an almost exponentially
decaying envelope. In the other limit, the WTD of a single quantum channel
subjected to a constant voltage is recovered. In both cases, the WTD stresses
the difference between the fluctuations induced by the scatterer and the ones
encoded in the incoming quantum state. A clear cross-over between these two
situations is studied with numerical and analytical calculations based on
scattering theory.Comment: 12 pages, 4 figure
Fingerprints of Majorana fermions in current-correlations measurements from a superconducting tunnel microscope
We compute various current correlation functions of electrons flowing from a
topological nanowire to the tip of a superconducting scanning tunnel microscope
and identify fingerprints of a Majorana bound state. In particular, the spin
resolved cross-correlations are shown to display a clear distinction between
the presence of a such an exotic state (negative correlations) and an Andreev
bound state (positive correlations). Similarity and differences with
measurements with a normal tunnel microscope are also discussed, like the
robustness to finite temperature for instance.Comment: 7 pages, 2 figure
The computability path ordering
This paper aims at carrying out termination proofs for simply typed
higher-order calculi automatically by using ordering comparisons. To this end,
we introduce the computability path ordering (CPO), a recursive relation on
terms obtained by lifting a precedence on function symbols. A first version,
core CPO, is essentially obtained from the higher-order recursive path ordering
(HORPO) by eliminating type checks from some recursive calls and by
incorporating the treatment of bound variables as in the com-putability
closure. The well-foundedness proof shows that core CPO captures the essence of
computability arguments \'a la Tait and Girard, therefore explaining its name.
We further show that no further type check can be eliminated from its recursive
calls without loosing well-foundedness, but for one for which we found no
counterexample yet. Two extensions of core CPO are then introduced which allow
one to consider: the first, higher-order inductive types; the second, a
precedence in which some function symbols are smaller than application and
abstraction
Conjugacy classes of trialitarian automorphisms and symmetric compositions
The trialitarian automorphisms considered in this paper are the outer
automorphisms of order 3 of adjoint classical groups of type D_4 over arbitrary
fields. A one-to-one correspondence is established between their conjugacy
classes and similarity classes of symmetric compositions on 8-dimensional
quadratic spaces. Using the known classification of symmetric compositions, we
distinguish two conjugacy classes of trialitarian automorphisms over
algebraically closed fields. For type I, the group of fixed points is of type
G_2, whereas it is of type A_2 for trialitarian automorphisms of type II
A global model for the combustion of gas mixtures released from forest fuels
International audienc
Patrimoine et ethnologie dans le Sud de la France
Ce texte, destiné à un ouvrage publié en Espagne, résume à la fois l'histoire récente de la construction des identités régionales dans le Midi de la France et les étapes successives des politiques de patrimonialisation impliquant l'ethnologi
Sacrifice et prophéties dans la France du XIXe siècle
Ce texte présente le vaste dossier des prophéties (souvent associées à des apparitions mariales) qui se sont multipliées en France à partir surtout des années 1840. Il insiste sur les liens entre ces messages souvent apocalyptiques, la diffusion d'une théologie du sacrifice et les positions politiques de l'Église en résistance contre les assauts de la modernité. Ce contexte global permet de s'interroger sur le cas des apparitions de Lourdes (1868), qui semblent avoir une signification assez différente
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