3,590 research outputs found
Projective construction of the Read-Rezayi fractional quantum Hall states and their excitations on the torus geometry
Multilayer fractional quantum Hall wave functions can be used to construct
the non-Abelian states of the Read-Rezayi series upon
symmetrization over the layer index. Unfortunately, this construction does not
yield the complete set of ground states on the torus. We develop
an alternative projective construction of Read-Rezayi states
that complements the existing one. On the multi-layer torus geometry, our
construction consists of introducing twisted boundary conditions connecting the
layers before performing the symmetrization. We give a comprehensive account of
this construction for bosonic states, and numerically show that the full ground
state and quasihole manifolds are recovered for all computationally accessible
system sizes. Furthermore, we analyze the neutral excitation modes above the
Moore-Read on the torus through an extensive exact diagonalization study. We
show numerically that our construction can be used to obtain excellent
approximations to these modes. Finally, we extend the new symmetrization scheme
to the plane and sphere geometries.Comment: 19 pages, 9 figure
Differential Evolution for Many-Particle Adaptive Quantum Metrology
We devise powerful algorithms based on differential evolution for adaptive
many-particle quantum metrology. Our new approach delivers adaptive quantum
metrology policies for feedback control that are orders-of-magnitude more
efficient and surpass the few-dozen-particle limitation arising in methods
based on particle-swarm optimization. We apply our method to the
binary-decision-tree model for quantum-enhanced phase estimation as well as to
a new problem: a decision tree for adaptive estimation of the unknown bias of a
quantum coin in a quantum walk and show how this latter case can be realized
experimentally.Comment: Fig. 2(a) is the cover of Physical Review Letters Vol. 110 Issue 2
Le cochon dans les listes lexicales: quelles logiques de classement?
International audienceĂ François Poplin, en tĂ©moignage amical de Michelion Dans une ferme un jour un cochon vadrouilla Dans la cuisine et l'Ă©curie il se gouilla Fumier, dĂ©chets tripatouilla, L'eau grasse jusqu'aux oreilles il barbouilla, Et puis revint cĂ©ans, Cochon comme devant⊠" Le porc " (III, 16) M. Colin. Fables de Krylov. Traduction et commentaire. Paris: Les Belles Lettres, 1978. Pp. 69â70. La place des suidĂ©s (la famille des cochons) dans les listes lexicales est complexe. Ces documents servaient d'abord Ă rĂ©flĂ©chir sur les mots et les signes, mais ils rĂ©vĂšlent aussi la perception du monde de ceux qui les ont Ă©laborĂ©s. Ainsi, il a dĂ©jĂ Ă©tĂ© notĂ© que le cochon, bien que domestiquĂ© depuis le IX e millĂ©naire av. J.-C. au Proche-Orient, est classĂ© dans la version canonique d'ur 5-ra parmi les animaux sauvages. 1 L'examen des listes lexicales du II e et du I er millĂ©naire met en Ă©vidence la place ambiguĂ« des cochons, presque toujours classĂ©s parmi les espĂšces sauvages, mais traitĂ©s parfois d'une façon qui les assimile aux animaux domestiques. Les suidĂ©s cĂŽtoient dans les listes des animaux trĂšs divers, comme les ours, les ron-* B. Lion, UniversitĂ© Paris 1 PanthĂ©on â Sorbonne, et C. Michel, CNRS. ArScAn-HAROC, Maison RenĂ©-GinouvĂšs ArchĂ©ologie et Ethnologie. 1 Ayant travaillĂ© avec plusieurs collĂšgues sur les suidĂ©s Ă l'occasion d'un col-loque (LionâMichel 2006), nous avons souhaitĂ© approfondir ce point. Et puisque les Pr. Kogan et Militarev ont consacrĂ© plusieurs publications aux noms d'ani-maux, la 53 e Rencontre Assyriologique Internationale Ă Moscou et Saint-PĂ©ters-bourg nous a semblĂ© une occasion tout indiquĂ©e (SED II)
Ammonia oxidation is not required for growth of Group 1.1c soil Thaumarchaeota
© FEMS 2015. FUNDING EBW is funded by Centre for Genome Enabled Biology and Medicine, University of Aberdeen.Peer reviewedPublisher PD
Statistics of low energy excitations for the directed polymer in a random medium ()
We consider a directed polymer of length in a random medium of space
dimension . The statistics of low energy excitations as a function of
their size is numerically evaluated. These excitations can be divided into
bulk and boundary excitations, with respective densities
and . We find that both densities follow the scaling
behavior , where is the exponent governing the
energy fluctuations at zero temperature (with the well-known exact value
in one dimension). In the limit , both scaling
functions and behave as , leading to the droplet power law
in the regime . Beyond their common singularity near , the two scaling functions
are very different : whereas decays
monotonically for , the function first decays for
, then grows for , and finally presents a power law
singularity near . The density
of excitations of length accordingly decays as
where
. We obtain , and , suggesting the possible relation
.Comment: 15 pages, 25 figure
On the multifractal statistics of the local order parameter at random critical points : application to wetting transitions with disorder
Disordered systems present multifractal properties at criticality. In
particular, as discovered by Ludwig (A.W.W. Ludwig, Nucl. Phys. B 330, 639
(1990)) on the case of diluted two-dimensional Potts model, the moments
of the local order parameter scale with a set
of non-trivial exponents . In this paper, we revisit
these ideas to incorporate more recent findings: (i) whenever a multifractal
measure normalized over space occurs in a random
system, it is crucial to distinguish between the typical values and the
disorder averaged values of the generalized moments , since
they may scale with different generalized dimensions and
(ii) as discovered by Wiseman and Domany (S. Wiseman and E. Domany, Phys Rev E
{\bf 52}, 3469 (1995)), the presence of an infinite correlation length induces
a lack of self-averaging at critical points for thermodynamic observables, in
particular for the order parameter. After this general discussion valid for any
random critical point, we apply these ideas to random polymer models that can
be studied numerically for large sizes and good statistics over the samples. We
study the bidimensional wetting or the Poland-Scheraga DNA model with loop
exponent (marginal disorder) and (relevant disorder). Finally,
we argue that the presence of finite Griffiths ordered clusters at criticality
determines the asymptotic value and the minimal value of the typical multifractal spectrum
.Comment: 17 pages, 20 figure
Numerical study of the disordered Poland-Scheraga model of DNA denaturation
We numerically study the binary disordered Poland-Scheraga model of DNA
denaturation, in the regime where the pure model displays a first order
transition (loop exponent ). We use a Fixman-Freire scheme for the
entropy of loops and consider chain length up to , with
averages over samples. We present in parallel the results of various
observables for two boundary conditions, namely bound-bound (bb) and
bound-unbound (bu), because they present very different finite-size behaviors,
both in the pure case and in the disordered case. Our main conclusion is that
the transition remains first order in the disordered case: in the (bu) case,
the disorder averaged energy and contact densities present crossings for
different values of without rescaling. In addition, we obtain that these
disorder averaged observables do not satisfy finite size scaling, as a
consequence of strong sample to sample fluctuations of the pseudo-critical
temperature. For a given sample, we propose a procedure to identify its
pseudo-critical temperature, and show that this sample then obeys first order
transition finite size scaling behavior. Finally, we obtain that the disorder
averaged critical loop distribution is still governed by in
the regime , as in the pure case.Comment: 12 pages, 13 figures. Revised versio
Directed polymer in a random medium of dimension 1+1 and 1+3: weights statistics in the low-temperature phase
We consider the low-temperature disorder-dominated phase of the
directed polymer in a random potentiel in dimension 1+1 (where )
and 1+3 (where ). To characterize the localization properties of
the polymer of length , we analyse the statistics of the weights of the last monomer as follows. We numerically compute the probability
distributions of the maximal weight , the probability distribution of the parameter as well as the average values of the higher order
moments . We find that there exists a
temperature such that (i) for , the distributions
and present the characteristic Derrida-Flyvbjerg
singularities at and for . In particular, there
exists a temperature-dependent exponent that governs the main
singularities and as well as the power-law decay of the moments . The exponent grows from the value
up to . (ii) for , the
distribution vanishes at some value , and accordingly the
moments decay exponentially as in . The
histograms of spatial correlations also display Derrida-Flyvbjerg singularities
for . Both below and above , the study of typical and
averaged correlations is in full agreement with the droplet scaling theory.Comment: 13 pages, 29 figure
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