1,720,975 research outputs found
Transport and entanglement across integrable impurities from Generalized Hydrodynamics
Full text linkQuantum impurity models (QIMs) are ubiquitous throughout physics. As
simplified toy models they provide crucial insights for understanding more
complicated strongly correlated systems, while in their own right are accurate
descriptions of many experimental platforms. In equilibrium, their physics is
well understood and have proven a testing ground for many powerful theoretical
tools, both numerical and analytical, in use today. Their non-equilibrium
physics is much less studied and understood. However, the recent advancements
in non equilibrium integrable quantum systems through the development of
generalized hydrodynamics (GHD) coupled with the fact that many archetypal QIMs
are in fact integrable presents an enticing opportunity to enhance our
understanding of these systems. We take a step towards this by expanding the
framework of GHD to incorporate integrable interacting QIMs. We present a set
of Bethe-Boltzmann type equations which incorporate the effects of impurity
scattering and discuss the new aspects which include entropy production. These
impurity GHD equations are then used to study a bipartioning quench wherein a
relevant backscattering impurity is included at the location of the
bipartition. The density and current profiles are studied as a function of the
impurity strength and expressions for the entanglement entropy and full
counting statistics are derived.Comment: 4.5+9 pages, 2 figure
Solution of the BEC to BCS Quench in One Dimension
Full text linkA gas of interacting fermions confined in a quasi one-dimensional geometry
shows a BEC to BCS crossover upon slowly driving its coupling constant through
a confinement-induced resonance. On one side of the crossover the fermions form
tightly-bound bosonic molecules behaving as a repulsive Bose gas, while on the
other they form Cooper pairs, whose size is much larger than the average
inter-particle distance. Here we consider the situation arising when the
coupling constant is varied suddenly from the BEC to the BCS value. Namely, we
study a BEC-to-BCS quench. By exploiting a suitable continuum limit of recently
discovered solvable quenches in the Hubbard model, we show that the local
stationary state reached at large times after the quench can be determined
exactly by means of the Quench Action approach. We provide an
experimentally-accessible characterisation of the stationary state by computing
local pair correlation function as well as the quasi-particle distribution
functions. We find that the steady state is increasingly dominated by two
particle spin singlet bound states for stronger interaction strength but that
bound state formation is inhibited at larger BEC density. The bound state
rapidity distribution displays quartic power law decay suggesting a violation
of Tan's contact relations.Comment: 5 pages, 2 figure
Nonequilibrium Full Counting Statistics and Symmetry-Resolved Entanglement from Space-Time Duality
Full text linkDue to its probabilistic nature, a measurement process in quantum mechanics
produces a distribution of possible outcomes. This distribution - or its
Fourier transform known as full counting statistics (FCS) - contains much more
information than say the mean value of the measured observable and accessing it
is sometimes the only way to obtain relevant information about the system. In
fact, the FCS is the limit of an even more general family of observables - the
charged moments - that characterise how quantum entanglement is split in
different symmetry sectors in the presence of a global symmetry. Here we
consider the evolution of the FCS and of the charged moments of a U(1) charge
truncated to a finite region after a global quantum quench. For large scales
these quantities take a simple large-deviation form, showing two different
regimes as functions of time: while for times much larger than the size of the
region they approach a stationary value set by the local equilibrium state, for
times shorter than region size they show a non-trivial dependence on time. We
show that, whenever the initial state is also U(1) symmetric, the leading order
in time of FCS and charged moments in the out-of-equilibrium regime can be
determined by means of a space-time duality. Namely, it coincides with the
stationary value in the system where the roles of time and space are exchanged.
We use this observation to find some general properties of FCS and charged
moments out-of-equilibrium, and to derive an exact expression for these
quantities in interacting integrable models. We test this expression against
exact results in the Rule 54 quantum cellular automaton and exact numerics in
the XXZ spin-1/2 chain.Comment: 7+12 pages, 3+5 figures; v2 references added; v3 presentation
improved, as appears in PR
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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