12,980 research outputs found
Full Counting Statistics of Cooper Pair Shuttling
The Cooper pair shuttle is a simple model system that combines features of
coherent and incoherent transport. We evaluate the full counting statistics
(FCS) of charge transfer via the shuttle in the incoherent regime. We describe
two limiting cases when the FCS allows for classical interpretation. Generally,
the classical interpretation fails yielding negative and imaginary
"probabilities". This signals that superconducting coherence survives even in
incoherent regime. We evaluate the current noise in some detail.Comment: 4 pages, 3 figures; v2 (published version) corrected misprint
Linear Quantum Entropy and Non-Hermitian Hamiltonians
We consider the description of open quantum systems with probability sinks
(or sources) in terms of general non-Hermitian Hamiltonians.~Within such a
framework, we study novel possible definitions of the quantum linear entropy as
an indicator of the flow of information during the dynamics. Such linear
entropy functionals are necessary in the case of a partially Wigner-transformed
non-Hermitian Hamiltonian (which is typically useful within a mixed
quantum-classical representation). Both the case of a system represented by a
pure non-Hermitian Hamiltonian as well as that of the case of non-Hermitian
dynamics in a classical bath are explicitly considered.Comment: Entropy, Special Issue "Entropy in Quantum Systems and Quantum Field
Theory (QFT)
Rigorous construction of ground state correlations in graphene: renormalization of the velocities and Ward Identities
We consider the 2D Hubbard model on the honeycomb lattice, as a model for
single layer graphene with screened Coulomb interactions; at half filling and
weak coupling, we construct its ground state correlations by a convergent
multiscale expansion, rigorously excluding the presence of magnetic or
superconducting instabilities or the formation of a mass gap. The Fermi
velocity, which can be written in terms of a convergent series expansion,
remains close to its non-interacting value and turns out to be isotropic. On
the contrary, the interaction produces an asymmetry between the two components
of the charge velocity, in contrast with the predictions based on relativistic
or continuum approximations.Comment: 4 pages, 1 figure; version published on Phys. Rev. B; erratum adde
Multi-parametric R-matrix for the sl(2|1) Yangian
We study the Yangian of the sl(2|1) Lie superalgebra in a multi-parametric
four-dimensional representation. We use Drinfeld's second realization to
independently rederive the R-matrix, and to obtain the antiparticle
representation, the crossing and the unitarity condition. We consistently apply
the Yangian antipode and its inverse to the individual particles involved in
the scattering. We explicitly find a scalar factor solving the crossing and
unitarity conditions, and study the analytic structure of the resulting dressed
R-matrix. The formulas we obtain bear some similarities with those familiar
from the study of integrable structures in the AdS/CFT correspondence, although
they present obvious crucial differences.Comment: 25 pages, LaTeX, no figures; v2: typos corrected, minor changes,
added pole analysis of the dressed R-matrix; v3: clarifications added, typos
corrected, references added; v4: typos corrected, minor changes, version to
appear in J. Math. Phy
Real-Time Containers: A Survey
Container-based virtualization has gained a significant importance in a deployment of software applications in cloud-based environments. The technology fully relies on operating system features and does not require a virtualization layer (hypervisor) that introduces a performance degradation. Container-based virtualization allows to co-locate multiple isolated containers on a single computation node as well as to decompose an application into multiple containers distributed among several hosts (e.g., in fog computing layer). Such a technology seems very promising in other domains as well, e.g., in industrial automation, automotive, and aviation industry where mixed criticality containerized applications from various vendors can be co-located on shared resources.
However, such industrial domains often require real-time behavior (i.e, a capability to meet predefined deadlines). These capabilities are not fully supported by the container-based virtualization yet. In this work, we provide a systematic literature survey study that summarizes the effort of the research community on bringing real-time properties in container-based virtualization. We categorize existing work into main research areas and identify possible immature points of the technology
The Italian primary school-size distribution and the city-size: a complex nexus
We characterize the statistical law according to which Italian primary
school-size distributes. We find that the school-size can be approximated by a
log-normal distribution, with a fat lower tail that collects a large number of
very small schools. The upper tail of the school-size distribution decreases
exponentially and the growth rates are distributed with a Laplace PDF. These
distributions are similar to those observed for firms and are consistent with a
Bose-Einstein preferential attachment process. The body of the distribution
features a bimodal shape suggesting some source of heterogeneity in the school
organization that we uncover by an in-depth analysis of the relation between
schools-size and city-size. We propose a novel cluster methodology and a new
spatial interaction approach among schools which outline the variety of
policies implemented in Italy. Different regional policies are also discussed
shedding lights on the relation between policy and geographical features.Comment: 16 pages, 10 figure
Optimal Online Selection of a Monotone Subsequence: a Central Limit Theorem
Consider a sequence of independent random variables with a common
continuous distribution , and consider the task of choosing an increasing
subsequence where the observations are revealed sequentially and where an
observation must be accepted or rejected when it is first revealed. There is a
unique selection policy that is optimal in the sense that it
maximizes the expected value of , the number of selected
observations. We investigate the distribution of ; in particular,
we obtain a central limit theorem for and a detailed
understanding of its mean and variance for large . Our results and methods
are complementary to the work of Bruss and Delbaen (2004) where an analogous
central limit theorem is found for monotone increasing selections from a finite
sequence with cardinality where is a Poisson random variable that is
independent of the sequence.Comment: 26 page
Three-quark potentials in an effective Polyakov loop model
Three-quark potentials are studied in great details in the three-dimensional
pure gauge theory at finite temperature, for the cases of static
sources in the fundamental and adjoint representations. For this purpose, the
corresponding Polyakov loop model in its simplest version is adopted. The
potentials in question, as well as the conventional quark--anti-quark
potentials, are calculated numerically both in the confinement and
deconfinement phases. Results are compared to available analytical predictions
at strong coupling and in the limit of large number of colors . The
three-quark potential is tested against the expected and laws and
the string tension entering these laws is compared to the conventional
string tension. As a byproduct of this investigation, essential
features of the critical behaviour across the deconfinement transition are
elucidated.Comment: 28 pages, 18 figures, 4 tables; some text and a few references added;
version accepted for publication on Nucl. Phys.
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