The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Renes, Joseph M. - One of the best experts on this subject based on the ideXlab platform.
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Work cost of thermal operations in quantum thermodynamics
2019Co-Authors: Renes, Joseph M.Abstract:Abstract.: Adopting a resource theory framework of thermodynamics for quantum and nano systems pioneered by Janzing et al. (Int. J. Th. Phys. 39, 2717 (2000)), we formulate the cost in the useful work of transforming one resource state into another as a linear program of convex optimization. This approach is based on the characterization of thermal Quasiorder given by Janzing et al. and later by Horodecki and Oppenheim (Nat. Comm. 4, 2059 (2013)). Both characterizations are related to an extended version of majorization studied by Ruch, Schranner and Seligman under the name mixing distance (J. Chem. Phys. 69, 386 (1978))
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Beyond heat baths: Generalized resource theories for small-scale thermodynamics
'American Physical Society (APS)', 2016Co-Authors: Yunger Halpern Nicole, Renes, Joseph M.Abstract:Thermodynamics has recently been extended to small scales with resource theories that model heat exchanges. Real physical systems exchange diverse quantities: heat, particles, angular momentum, etc. We generalize thermodynamic resource theories to exchanges of observables other than heat, to baths other than heat baths, and to free energies other than the Helmholtz free energy. These generalizations are illustrated with “grand-potential” theories that model movements of heat and particles. Free operations include unitaries that conserve energy and particle number. From this conservation law and from resource-theory principles, the grand-canonical form of the free states is derived. States are shown to form a Quasiorder characterized by free operations, d majorization, the hypothesis-testing entropy, and rescaled Lorenz curves. We calculate the work distillable from—and we bound the work cost of creating—a state. These work quantities can differ but converge to the grand potential in the thermodynamic limit. Extending thermodynamic resource theories beyond heat baths, we open diverse realistic systems to modeling with one-shot statistical mechanics. Prospective applications such as electrochemical batteries are hoped to bridge one-shot theory to experiments
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Beyond heat baths: Generalized resource theories for small-scale thermodynamics
'American Physical Society (APS)', 2016Co-Authors: Halpern, Nicole Yunger, Renes, Joseph M.Abstract:Thermodynamics has recently been extended to small scales with resource theories that model heat exchanges. Real physical systems exchange diverse quantities: heat, particles, angular momentum, etc. We generalize thermodynamic resource theories to exchanges of observables other than heat, to baths other than heat baths, and to free energies other than the Helmholtz free energy. These generalizations are illustrated with "grand-potential" theories that model movements of heat and particles. Free operations include unitaries that conserve energy and particle number. From this conservation law and from resource-theory principles, the grand-canonical form of the free states is derived. States are shown to form a Quasiorder characterized by free operations, d-majorization, the hypothesis-testing entropy, and rescaled Lorenz curves. We calculate the work distillable from, and we bound the work cost of creating, a state. These work quantities can differ but converge to the grand potential in the thermodynamic limit. Extending thermodynamic resource theories beyond heat baths, we open diverse realistic systems to modeling with one-shot statistical mechanics. Prospective applications such as electrochemical batteries are hoped to bridge one-shot theory to experiments.Comment: 13 pages + appendice
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Work Cost of Thermal Operations in Quantum and Nano Thermodynamics
'Springer Science and Business Media LLC', 2014Co-Authors: Renes, Joseph M.Abstract:Adopting a resource theory framework of thermodynamics for quantum and nano systems pioneered by Janzing et al. [Int. J. Th. Phys. 39, 2717 (2000)], we formulate the cost in useful work of transforming one resource state into another as a linear program of convex optimization. This approach is based on the characterization of thermal Quasiorder given by Janzing et al. and later by Horodecki and Oppenheim [Nat. Comm. 4, 2059 (2013)]. Both characterizations are related to an extended version of majorization studied by Ruch, Schranner, and Seligman under the name mixing distance [J. Chem. Phys. 69, 386 (1978)].Comment: 5 pages, 2 figures. Presented at "Noise Information and Complexity at Quantum Scale, 2013
Ming Ju Chou - One of the best experts on this subject based on the ideXlab platform.
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the Quasiorder disorder phase transition and peak effect in mgb2 type ii superconducting materials and thin films
Annalen der Physik, 2010Co-Authors: Ming Ju Chou, Hernger HorngAbstract:The peak effect and the Quasiorder-disorder first-order phase transition for Magnesium diboride, MgB2, superconducting bulk materials have been studied. The peak values of the critical current density Jc, and the exact peak positions together with its corresponding half-widths for a constant temperature as well as for a constant applied magnetic field have been calculated by considering the quantum, thermal as well as random fluctuations of the vortex lattice. The results for MgB2 bulk materials are in agreement with the experiment. The peak effect for MgB2 superconducting thin films is also predicted theoretically. The expected peak effect may be observed provided that doping or other experimental techniques are applied to improve the flux pinning of the MgB2 superconducting thin films.
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Quasiorder disorder phase transition and induced peak effect in type ii superconductors
Physica C-superconductivity and Its Applications, 2007Co-Authors: Wei Yeu Chen, Ming Ju Chou, Shiping FengAbstract:Abstract We have developed a quantum theory for vortex dynamics and applied this theory to discuss Quasiorder–disorder phase transitions and peak effects in type-II superconductors. The peak value of the critical current density, the exact peak position, and the corresponding half-width for type-II superconducting films and bulk materials have been calculated. The results are in good agreement with current experiments.
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Directional-dependent thermally activated motion of vortex bundles and theory of anomalous Hall effect in type-II conventional and high-Tc superconductors
2007Co-Authors: Chen*, Wei Yeu, Ming Ju ChouAbstract:The anomalous Hall effect for type-II conventional and high-Tc superconductors is studied based upon the theory of thermally activated motion of vortex bundles jumping over the directional-dependent energy barrier. It is shown that the Hall anomaly is universal for type-II conventional and high-Tc superconductors as well as for superconducting bulk materials and thin films, provided certain conditions are satisfied. We find that the directional-dependent potential barrier of the vortex bundles renormalizes the Hall and longitudinal resistivities, and Hall anomaly for superconductors is induced by the competition between the Magnus force and the random collective pinning force of the vortex bundle. We also find that the domain of anomalous Hall effect includes two regions: the region of thermally activated motion of the small vortex bundles and that of the large vortex bundles separated by the contour of the Quasiorder-disorder first-order phase transition, or the peak effect of the vortex system. The Hall and longitudinal resistivities as functions of temperature as well as applied magnetic field have been calculated for type-II superconducting films and bulk materials. The conditions for occurring the double sign reversal or reentry phenomenon is also investigated. All the results are in agreement with the experiments.Comment: 36 pages, 10 figures, 5 table
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the Quasiorder disorder phase transition and the peak effect in type ii conventional and high tc superconductors
Superconductor Science and Technology, 2006Co-Authors: Wei Yeu Chen, Ming Ju ChouAbstract:The peak effect and the Quasiorder–disorder phase transition for type-II conventional and high-Tc superconductors have been investigated by taking into account both the quenched disorder and the thermal fluctuations of the vortex lattice. The peak value of the critical current density, the exact peak position and its corresponding half-width for a constant temperature as well as for a constant applied magnetic field have been calculated for type-II superconducting films and bulk materials in the non-dispersive regime of the vortex bundle, and all of the results from the experiment are in agreement.
V. L. Selivanov - One of the best experts on this subject based on the ideXlab platform.
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A Q-Wadge Hierarchy in Quasi-Polish Spaces.
arXiv: Logic, 2019Co-Authors: V. L. SelivanovAbstract:The Wadge hierarchy was originally defined and studied only in the Baire space (and some other zero-dimensional spaces). We extend it here to arbitrary topological spaces by providing a set-theoretic definition of all its levels. We show that our extension behaves well in second countable spaces and especially in quasi-Polish spaces. In particular, all levels are preserved by continuous open surjections between second countable spaces which implies e.g. several Hausdorff-Kuratowski-type theorems in quasi-Polish spaces. In fact, many results hold not only for the Wadge hierarchy of sets but also for its extension to Borel functions from a space to a countable better Quasiorder Q.
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Definability of closure operations in the h-Quasiorder of labeled forests
Algebra and Logic, 2010Co-Authors: A. V. Zhukov, O. V. Kudinov, V. L. SelivanovAbstract:We prove that natural closure operations on quotient structures of the h -Quasiorder of finite and (at most) countable k -labeled forests ( k ≥ 3) are definable provided that minimal nonsmallest elements are allowed as parameters. This strengthens our previous result which holds that each element of the h -Quasiorder of finite k -labeled forests is definable in the first-order language, and each element of the h -Quasiorder of (at most) countable k -labeled forests is definable in the language L _ω1ω; in both cases k ≥ 3 and minimal nonsmallest elements are allowed as parameters. Similar results hold true for two other relevant structures: the h -Quasiorder of finite (resp. countable) k -labeled trees and k -labeled trees with a fixed label on the root element.
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definability in the h Quasiorder of labeled forests
Annals of Pure and Applied Logic, 2009Co-Authors: O. V. Kudinov, V. L. Selivanov, A. V. ZhukovAbstract:Abstract We prove that for any k ≥ 3 each element of the h -Quasiorder of finite k -labeled forests is definable in the ordinary first order language and, respectively, each element of the h -Quasiorder of (at most) countable k -labeled forests is definable in the language L ω 1 ω , in both cases provided that the minimal non-smallest elements are allowed as parameters. As corollaries, we characterize the automorphism groups of both structures and show that the structure of finite k -forests is atomic. Similar results hold true for two other relevant structures: the h -Quasiorder of finite (resp. countable) k -labeled trees and of finite (resp. countable) k -labeled trees with a fixed label of the root element.
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undecidability in the homomorphic Quasiorder of finite labelled forests
Journal of Logic and Computation, 2007Co-Authors: O. V. Kudinov, V. L. SelivanovAbstract:We prove that the homomorphic Quasiorder of finite k-labelled forests has a hereditary undecidable first-order theory for k ≥ 3, in contrast to the known decidability result for k = 2. We establish also hereditary undecidability (again for every k ≥ 3) of first-order theories of two other relevant structures: the homomorphic Quasiorder of finite k-labelled trees, and of finite k-labelled trees with a fixed label of the root element. Finally, all three first-order theories are shown to be computably isomorphic to the first-order arithmetic.
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undecidability in the homomorphic Quasiorder of finite labeled forests
Conference on Computability in Europe, 2006Co-Authors: O. V. Kudinov, V. L. SelivanovAbstract:We prove that the homomorphic Quasiorder of finite k-labeled forests has undecidable elementary theory for k ≥3, in contrast to the known decidability result for k=2. We establish also undecidablity (again for every k ≥3) of elementary theories of two other relevant structures: the homomorphic Quasiorder of finite k-labeled trees, and of finite k-labeled trees with a fixed label of the root element.
Valero Pedro - One of the best experts on this subject based on the ideXlab platform.
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Complete Abstractions for Checking Language Inclusion
2021Co-Authors: Ganty Pierre, Ranzato Francesco, Valero PedroAbstract:We study the language inclusion problem $L_1 \subseteq L_2$ where $L_1$ is regular or context-free. Our approach relies on abstract interpretation and checks whether an overapproximating abstraction of $L_1$, obtained by overapproximating the Kleene iterates of its least fixpoint characterization, is included in $L_2$. We show that a language inclusion problem is decidable whenever this overapproximating abstraction satisfies a completeness condition (i.e., its loss of precision causes no false alarm) and prevents infinite ascending chains (i.e., it guarantees termination of least fixpoint computations). This overapproximating abstraction of languages can be defined using Quasiorder relations on words, where the abstraction gives the language of all the words "greater than or equal to" a given input word for that Quasiorder. We put forward a range of such Quasiorders that allow us to systematically design decision procedures for different language inclusion problems such as regular languages into regular languages or into trace sets of one-counter nets, and context-free languages into regular languages. In the case of inclusion between regular languages, some of the induced inclusion checking procedures correspond to well-known state-of-the-art algorithms like the so-called antichain algorithms. Finally, we provide an equivalent language inclusion checking algorithm based on a greatest fixpoint computation that relies on quotients of languages and, to the best of our knowledge, was not previously known.Comment: 39 pages, 4 figures, 6 algorithms, revised and extended version of our SAS 2019 paper (https://doi.org/10.1007/978-3-030-32304-2_8). arXiv admin note: text overlap with arXiv:2008.0882
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A Quasiorder-based Perspective on Residual Automata
2020Co-Authors: Ganty Pierre, Gutiérrez Elena, Valero PedroAbstract:In this work, we define a framework of automata constructions based on Quasiorders over words to provide new insights on the class of residual automata. We present a new residualization operation and a generalized double-reversal method for building the canonical residual automaton for a given language. Finally, we use our framework to offer a Quasiorder-based perspective on NL*, an online learning algorithm for residual automata. We conclude that Quasiorders are fundamental to residual automata as congruences are to deterministic automata
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On the Use of Quasiorders in Formal Language Theory
2020Co-Authors: Valero PedroAbstract:In this thesis we use Quasiorders on words to offer a new perspective on two well-studied problems from Formal Language Theory: deciding language inclusion and manipulating the finite automata representations of regular languages. First, we present a generic Quasiorder-based framework that, when instantiated with different Quasiorders, yields different algorithms (some of them new) for deciding language inclusion. We then instantiate this framework to devise an efficient algorithm for searching with regular expressions on grammar-compressed text. Finally, we define a framework of Quasiorder-based automata constructions to offer a new perspective on residual automata.Comment: PhD thesi
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Complete Abstractions for Checking Language Inclusion
2019Co-Authors: Ganty Pierre, Ranzato Francesco, Valero PedroAbstract:We study the language inclusion problem $L_1 \subseteq L_2$ where $L_1$ is regular or context-free. Our approach relies on abstract interpretation and checks whether an overapproximating abstraction of $L_1$, obtained by successively overapproximating the Kleene iterates of its least fixpoint characterization, is included in $L_2$. We show that a language inclusion problem is decidable whenever this overapproximating abstraction satisfies a completeness condition (i.e. its loss of precision causes no false alarm) and prevents infinite ascending chains (i.e. it guarantees termination of least fixpoint computations). Such overapproximating abstraction function on languages can be defined using Quasiorder relations on words where the abstraction gives the language of all words "greater than or equal to" a given input word for that Quasiorder. We put forward a range of Quasiorders that allow us to systematically design decision procedures for different language inclusion problems such as context-free languages into regular languages and regular languages into trace sets of one-counter nets. We also provide Quasiorders for which the induced inclusion checking procedure corresponds to well-known state-of-the-art algorithms like the so-called antichain algorithms. Finally, we provide an equivalent greatest fixpoint language inclusion check which relies on quotients of languages and, to the best of our knowledge, was not previously known.Comment: 29 page
Nemanja Škorić - One of the best experts on this subject based on the ideXlab platform.
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On finite reflexive homomorphism-homogeneous binary relational systems
Discrete Mathematics, 2011Co-Authors: Dragan Mašulović, Rajko Nenadov, Nemanja ŠkorićAbstract:A structure is called homogeneous if every isomorphism between finitely induced substructures of the structure extends to an automorphism of the structure. Recently, P.?J.?Cameron and J.?Nesetřil introduced a relaxed version of homogeneity: we say that a structure is homomorphism-homogeneous if every homomorphism between finitely induced substructures of the structure extends to an endomorphism of the structure.In this paper, we consider finite homomorphism-homogeneous relational systems with one reflexive binary relation. We show that for a large part of such relational systems (bidirectionally connected digraphs; a digraph is bidirectionally connected if each of its connected components can be traversed by ? -paths) the problem of deciding whether the system is homomorphism-homogeneous is coNP-complete. Consequently, for this class of relational systems there is no polynomially computable characterization (unless P = N P ). On the other hand, in case of bidirectionally disconnected digraphs we present the full characterization. Our main result states that if a digraph is bidirectionally disconnected, then it is homomorphism-homogeneous if and only if it is either a finite homomorphism-homogeneous Quasiorder, or an inflation of a homomorphism-homogeneous digraph with involution (a specific class of digraphs introduced later in the paper), or an inflation of a digraph whose only connected components are C 3 ? and? 1 ? .