840 research outputs found
Local Magnetization in the Boundary Ising Chain at Finite Temperature
We study the local magnetization in the 2-D Ising model at its critical
temperature on a semi-infinite cylinder geometry, and with a nonzero magnetic
field applied at the circular boundary of circumference . This model
is equivalent to the semi-infinite quantum critical 1-D transverse field Ising
model at temperature , with a symmetry-breaking field
applied at the point boundary. Using conformal field theory methods
we obtain the full scaling function for the local magnetization analytically in
the continuum limit, thereby refining the previous results of Leclair, Lesage
and Saleur in Ref. \onlinecite{Leclair}. The validity of our result as the
continuum limit of the 1-D lattice model is confirmed numerically, exploiting a
modified Jordan-Wigner representation. Applications of the result are
discussed.Comment: 9 pages, 3 figure
ANALISIS RISIKO BENCANA TANAH LONGSOR DI KABUPATEN MINAHASA
Kabupaten Minahasa adalah salah satu kabupaten yang berada di provinsi Sulawesi utara dimana wilayah tersebut memiliki topografi dengan tingkat kemiringan lereng diatas 40%. Bencana tanah longsor adalah salah satu bencana alam yang cukup sering terjadi di kabupaten Minahasa, namun sering kali ditemukan di lapangan permukiman-permukiman warga yang berada pada tingkat kemiringan lereng diatas 40% selalin itu pada kondisi lahan tersebut juga sering dijadikan sebagai lahan pertanian. Maka dari itu dalam penelitian ini bertujuan untuk mengidentifikasi wilayah berpotensi longsor di kabupaten Minahasa serta menentukan seberapa besar tingkat risio bencanan tanah longsor di kabupaten Minahasa. Untuk mencapai hasil dari penelitian ini maka metode yang akan digunakan adalah metode analisis spasial yang dipadukan dengan analisis skoring sesuai dengan Peraturan Kepala Badan Nasional Penanggulangan Bencana nomor 12 tahun 2012 tentang Pengkajian Risiko Bencana. Pada hasil penelitian yang didapat maka sudah dapat dilihat wilayah-wilayah yang memiliki tingkat risiko terjadinya bencana tanah longsor yaitu kecamatan Kakas Barat, kecamatan Kombi, kecamatan Tombulu, dan kecamatan Tondanao Utara yang dimana sebagian besar wilayah dengan tingkat kemiringan lereng diatas 40% selain menjadi lokasi permukiman juga diganakan sebagai lahan pertanianHal yang dapat disimpulkan dalam penelitian ini adalah wilayah-wilayah yang berisiko tinggi mengalamin bencana tanah longsor adalah wilayah-wilayah yang memiliki lahan produktif yang cukup luas di antaranya kecamatan Tombulu, kecamatan Kombi, kecamatan Kakas Baran dan kecamatan Pineleng.Kata Kunci : Risiko, Bencana, Tanah Longso
Anomalous decay of a prepared state due to non-Ohmic coupling to the continuum
We study the decay of a prepared state into a continuum {E_k} in the
case of non-Ohmic models. This means that the coupling is with . We find that irrespective of model details
there is a universal generalized Wigner time that characterizes the
evolution of the survival probability . The generic decay behavior
which is implied by rate equation phenomenology is a slowing down stretched
exponential, reflecting the gradual resolution of the bandprofile. But
depending on non-universal features of the model a power-law decay might take
over: it is only for an Ohmic coupling to the continuum that we get a robust
exponential decay that is insensitive to the nature of the intra-continuum
couplings. The analysis highlights the co-existence of perturbative and
non-perturbative features in the dynamics. It turns out that there are special
circumstances in which is reflected in the spreading process and not only
in the survival probability, contrary to the naive linear response theory
expectation.Comment: 13 pages, 11 figure
The interaction between colloids in polar mixtures above Tc
We calculate the interaction potential between two colloids immersed in an
aqueous mixture containing salt near or above the critical temperature. We find
an attractive interaction far from the coexistence curve due to the combination
of preferential solvent adsorption at the colloids' surface and preferential
ion solvation. We show that the ion-specific interaction strongly depends on
the amount of salt added as well as on the mixture composition. Our results are
in accord with recent experiments. For a highly antagonistic salt of
hydrophilic anions and hydrophobic cations, a repulsive interaction at an
intermediate inter-colloid distance is predicted even though both the
electrostatic and adsorption forces alone are attractive.Comment: 9 pages, 6 figure
On the algorithmic construction of classifying spaces and the isomorphism problem for biautomatic groups
We show that the isomorphism problem is solvable in the class of central
extensions of word-hyperbolic groups, and that the isomorphism problem for
biautomatic groups reduces to that for biautomatic groups with finite centre.
We describe an algorithm that, given an arbitrary finite presentation of an
automatic group , will construct explicit finite models for the skeleta
of and hence compute the integral homology and cohomology of
.Comment: 21 pages, 4 figure
Solution sets for equations over free groups are EDT0L languages
© World Scientific Publishing Company. We show that, given an equation over a finitely generated free group, the set of all solutions in reduced words forms an effectively constructible EDT0L language. In particular, the set of all solutions in reduced words is an indexed language in the sense of Aho. The language characterization we give, as well as further questions about the existence or finiteness of solutions, follow from our explicit construction of a finite directed graph which encodes all the solutions. Our result incorporates the recently invented recompression technique of Jez, and a new way to integrate solutions of linear Diophantine equations into the process. As a byproduct of our techniques, we improve the complexity from quadratic nondeterministic space in previous works to NSPACE(n log n) here
Counting statistics in multiple path geometries and the fluctuations of the integrated current in a quantum stirring device
The amount of particles that are transported via a path of motion is
characterized by its expectation value and by its variance . We
analyze what happens if a particle has two optional paths available to get from
one site to another site, and in particular what is for the current
which is induced in a quantum stirring device. It turns out that coherent
splitting and the stirring effect are intimately related and cannot be
understood within the framework of the prevailing probabilistic theory.Comment: 11 pages, 2 figures, published version, Latex Eq# correcte
Quantum decay into a non-flat continuum
We study the decay of a prepared state into non-flat continuum. We find that
the survival probability might exhibit either stretched-exponential or
power-law decay, depending on non-universal features of the model. Still there
is a universal characteristic time that does not depend on the functional
form. It is only for a flat continuum that we get a robust exponential decay
that is insensitive to the nature of the intra-continuum couplings. The
analysis highlights the co-existence of perturbative and non-perturbative
features in the local density of states, and the non-linear dependence of
on the strength of the coupling.Comment: 10 pages, 4 figure
Top-transmon: hybrid superconducting qubit for parity-protected quantum computation
Qubits constructed from uncoupled Majorana fermions are protected from
decoherence, but to perform a quantum computation this topological protection
needs to be broken. Parity-protected quantum computation breaks the protection
in a minimally invasive way, by coupling directly to the fermion parity of the
system --- irrespective of any quasiparticle excitations. Here we propose to
use a superconducting charge qubit in a transmission line resonator (a socalled
transmon) to perform parity-protected rotations and read-out of a topological
(top) qubit. The advantage over an earlier proposal using a flux qubit is that
the coupling can be switched on and off with exponential accuracy, promising a
reduced sensitivity to charge noise.Comment: 7 pages, 5 figure
Velocity correlations in granular materials
A system of inelastic hard disks in a thin pipe capped by hot walls is
studied with the aim of investigating velocity correlations between particles.
Two effects lead to such correlations: inelastic collisions help to build
localized correlations, while momentum conservation and diffusion produce long
ranged correlations. In the quasi-elastic limit, the velocity correlation is
weak, but it is still important since it is of the same order as the deviation
from uniformity. For system with stronger inelasticity, the pipe contains a
clump of particles in highly correlated motion. A theory with empirical
parameters is developed. This theory is composed of equations similar to the
usual hydrodynamic laws of conservation of particles, energy, and momentum.
Numerical results show that the theory describes the dynamics satisfactorily in
the quasi-elastic limit, however only qualitatively for stronger inelasticity.Comment: 12 pages (REVTeX), 15 figures (Postscript). submitted to Phys. Rev.
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