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Quantum Criticality and Black Holes

Sachdev, Subir; Müller, Markus
Fonte: Institute of Physics Publicador: Institute of Physics
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
45.51%
Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport coefficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the anti-de Sitter/conformal field theory duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport coefficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid–insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance.; Physics

Quantum Annealing: from Viewpoints of Statistical Physics, Condensed Matter Physics, and Computational Physics

Tanaka, Shu; Tamura, Ryo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/04/2012
Relevância na Pesquisa
65.51%
In this paper, we review some features of quantum annealing and related topics from viewpoints of statistical physics, condensed matter physics, and computational physics. We can obtain a better solution of optimization problems in many cases by using the quantum annealing. Actually the efficiency of the quantum annealing has been demonstrated for problems based on statistical physics. Then the quantum annealing has been expected to be an efficient and generic solver of optimization problems. Since many implementation methods of the quantum annealing have been developed and will be proposed in the future, theoretical frameworks of wide area of science and experimental technologies will be evolved through studies of the quantum annealing.; Comment: 57pages, 15figures, to appear in "Lectures on Quantum Computing, Thermodynamics and Statistical Physics," Kinki University Series on Quantum Computing (World Scientific, 2012)

Trends in condensed matter physics: is research going faster and faster?

Attaccalite, C.; Barland, S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/11/2012
Relevância na Pesquisa
75.51%
In this paper we study research trends in condensed matter physics. Trends are analyzed by means of the the number of publications in the different sub-fields as function of the years. We found that many research topics have a similar behavior with an initial fast growth and a next slower exponential decay. We derived a simple model to describe this behavior and built up some predictions for future trends.

Condensed Matter Physics - Biology Resonance

Baskaran, G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 02/01/2000
Relevância na Pesquisa
65.51%
The field of condensed matter physics had its genesis this century and it has had a remarkable evolution. A closer look at its growth reveals a hidden aim in the collective consciousness of the field - a part of the development this century is a kind of warm up exercise to understand the nature of living condensed matter, namely the field of biology, by a growing new breed of scientists in the coming century. Through some examples the vitality of this interaction will be pointed out.; Comment: 4 pages; Based on a talk given at the Annual Meeting of the Indian National Science Academy at Madras during 29-31 Dec 1998. (To appear in the International Journal of Modern Physics B)

Performance Acceleration of Kernel Polynomial Method Applying Graphics Processing Units

Zhang, Shixun; Yamagiwa, Shinichi; Okumura, Masahiko; Yunoki, Seiji
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/05/2011
Relevância na Pesquisa
55.48%
The Kernel Polynomial Method (KPM) is one of the fast diagonalization methods used for simulations of quantum systems in research fields of condensed matter physics and chemistry. The algorithm has a difficulty to be parallelized on a cluster computer or a supercomputer due to the fine-gain recursive calculations. This paper proposes an implementation of the KPM on the recent graphics processing units (GPU) where the recursive calculations are able to be parallelized in the massively parallel environment. This paper also illustrates performance evaluations regarding the cases when the actual simulation parameters are applied, the one for increased intensive calculations and the one for increased amount of memory usage. Finally, it concludes that the performance on GPU promises very high performance compared to the one on CPU and reduces the overall simulation time.; Comment: IPDPS/APDCM11, pp. 564-571, Anchorage USA, May 2011

Exploiting Grids for applications in Condensed Matter Physics

Pujari, Bhalchandra S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/02/2010
Relevância na Pesquisa
75.56%
Grids - the collection of heterogeneous computers spread across the globe - present a new paradigm for the large scale problems in variety of fields. We discuss two representative cases in the area of condensed matter physics outlining the widespread applications of the Grids. Both the problems involve calculations based on commonly used Density Functional Theory and hence can be considered to be of general interest. We demonstrate the suitability of Grids for the problems discussed and provide a general algorithm to implement and manage such large scale problems.

First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase

Hsieh, D.; Xia, Y.; Wray, L.; Qian, D.; Pal, A.; Dil, J. H.; Meier, F.; Osterwalder, J.; Bihlmayer, G.; Kane, C. L.; Hor, Y. S.; Cava, R. J.; Hasan, M. Z.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/02/2009
Relevância na Pesquisa
45.52%
A topologically ordered material is characterized by a rare quantum organization of electrons that evades the conventional spontaneously broken symmetry based classification of condensed matter. Exotic spin transport phenomena such as the dissipationless quantum spin Hall effect have been speculated to originate from a novel topological order whose identification requires a spin sensitive measurement, which does not exist to this date in any system (neither in Hg(Cd)Te quantum wells nor in the topological insulator BiSb). Using Mott polarimetry, we probe the spin degrees of freedom of these quantum spin Hall states and demonstrate that topological quantum numbers are uniquely determined from spin texture imaging measurements. Applying this method to the Bi{1-x}Sb{x} series, we identify the origin of its novel order and unusual chiral properties. These results taken together constitute the first observation of surface electrons collectively carrying a geometrical quantum (Berry's) phase and definite chirality (mirror Chern number, n_M =-1), which are the key electronic properties for realizing topological computing bits with intrinsic spin Hall-like topological phenomena. Our spin-resolved results not only provides the first clear proof of a topological insulating state in nature but also demonstrate the utility of spin-resolved ARPES technique in measuring the quantum spin Hall phases of matter.; Comment: 15 pages...

Ultracold Atomic Gases: Novel States of Matter

Mathey, L.; Tsai, S. -W.; Neto, A. H. Castro
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/03/2009
Relevância na Pesquisa
45.53%
Article to appear in the Encyclopedia of Complexity and Systems Science, Dr. R. A. Meyers (Ed.) (Springer Heidelberg, 2009).; Comment: 43 pages, 17 figures. To appear in the Encyclopedia of Complexity and Systems Science, Dr. R. A. Meyers (Ed.) (Springer Heidelberg, 2009)

The effect of 'Open Access' upon citation impact: An analysis of ArXiv's Condensed Matter Section

Moed, Henk F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/11/2006
Relevância na Pesquisa
55.56%
This article statistically analyses how the citation impact of articles deposited in the Condensed Matter section of the preprint server ArXiv (hosted by Cornell University), and subsequently published in a scientific journal, compares to that of articles in the same journal that were not deposited in that archive. Its principal aim is to further illustrate and roughly estimate the effect of two factors, 'early view' and 'quality bias', upon differences in citation impact between these two sets of papers, using citation data from Thomson Scientific's Web of Science. It presents estimates for a number of journals in the field of condensed matter physics. In order to discriminate between an 'open access' effect and an early view effect, longitudinal citation data was analysed covering a time period as long as 7 years. Quality bias was measured by calculating ArXiv citation impact differentials at the level of individual authors publishing in a journal, taking into account co-authorship. The analysis provided evidence of a strong quality bias and early view effect. Correcting for these effects, there is in a sample of 6 condensed matter physics journals studied in detail, no sign of a general 'open access advantage' of papers deposited in ArXiv. The study does provide evidence that ArXiv accelerates citation...

Soft Condensed Matter (Materia Condensata Soffice)

Cates, M. E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/11/2004
Relevância na Pesquisa
55.52%
This article was written for a multi-volume History of Science, and published in Italian translation: Storia della Scienza, Volume IX, La Grande Scienza, pp 645-656 (published by Istituto della Enciclopedia Italiana, Fondata da Giovanni Treccani, 2003). In it, I describe the evolution of soft matter physics as a discipline during the 20th century.

Dynamical Simulation of Nuclear "Pasta": Soft Condensed Matter in Dense Stars

Watanabe, Gentaro; Sonoda, Hidetaka
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.52%
More than twenty years ago, it was predicted that nuclei can adopt interesting shapes, such as rods or slabs, etc., in the cores of supernovae and the crusts of neutron stars. These non-spherical nuclei are referred to as nuclear "pasta". In recent years, we have been studying the dynamics of the pasta phases using a method called quantum molecular dynamics (QMD) and have opened up a new aspect of study for this system. Our findings include: dynamical formation of the pasta phases by cooling down the hot uniform nuclear matter; phase diagrams in the density versus temperature plane; structural transitions between the pasta phases induced by compression and elucidation of the mechanism by which they proceed. In the present article, we given an overview of the basic physics and astrophysics of the pasta phases and review our works for readers in other fields.; Comment: 33 pages, 18 figures, revised version, published in "Soft Condensed Matter: New Research", edited by K. I. Dillon (Nova Science Publishers, New York, 2007), high-res figures can be seen at http://www.nordita.dk/~gentaro/research/figs

First-principles calculation of entropy for liquid metals

Desjarlais, Michael P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.55%
We demonstrate the accurate calculation of entropies and free energies for a variety of liquid metals using an extension of the two phase thermodynamic (2PT) model based on a decomposition of the velocity autocorrelation function into gas-like (hard sphere) and solid-like (harmonic) subsystems. The hard sphere model for the gas-like component is shown to give systematically high entropies for liquid metals as a direct result of the unphysical Lorentzian high-frequency tail. Using a memory function framework we derive a generally applicable velocity autocorrelation and frequency spectrum for the diffusive component which recovers the low frequency (long time) behavior of the hard sphere model while providing for realistic short time coherence and high frequency tails to the spectrum. This approach provides a significant increase in the accuracy of the calculated entropies for liquid metals and is compared to ambient pressure data for liquid sodium, aluminum, gallium, tin, and iron. The use of this method for the determination of melt boundaries is demonstrated with a calculation of the high pressure bcc melt boundary for sodium. With the significantly improved accuracy available with the memory function treatment for softer interatomic potentials...

The Fermi Gases and Superfluids: Short Review of Experiment and Theory for Condensed Matter Physicists

Levin, K.; Hulet, Randall G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/02/2012
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65.54%
The study of ultracold atomic Fermi gases is a rapidly exploding subject which is defining new directions in condensed matter and atomic physics. Quite generally what makes these gases so important is their remarkable tunability and controllability. Using a Feshbach resonance one can tune the attractive two-body interactions from weak to strong and thereby make a smooth crossover from a BCS superfluid of Cooper pairs to a Bose-Einstein condensed superfluid. Furthermore, one can tune the population of the two spin states, allowing observation of exotic spin-polarized superfluids, such as the Fulde Ferrell Larkin Ovchinnikov (FFLO) phase. A wide array of powerful characterization tools, which often have direct condensed matter analogues, are available to the experimenter. In this Chapter, we present a general review of the status of these Fermi gases with the aim of communicating the excitement and great potential of the field.; Comment: 34 pages, 15 figures. To appear as a chapter in "Contemporary Concepts of Condensed Matter Science", Elsevier

Quantum Information Meets Quantum Matter -- From Quantum Entanglement to Topological Phase in Many-Body Systems

Zeng, Bei; Chen, Xie; Zhou, Duan-Lu; Wen, Xiao-Gang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.56%
This is the draft version of a textbook, which aims to introduce the quantum information science viewpoints on condensed matter physics to graduate students in physics (or interested researchers). We keep the writing in a self-consistent way, requiring minimum background in quantum information science. Basic knowledge in undergraduate quantum physics and condensed matter physics is assumed. We start slowly from the basic ideas in quantum information theory, but wish to eventually bring the readers to the frontiers of research in condensed matter physics, including topological phases of matter, tensor networks, and symmetry-protected topological phases.; Comment: Hyperref added. This draft is by no means final. Substantial scientific and format changes are still to be made. We have received many helpful comments. We are very grateful for them and will incorporate them into later versions. Please keep sending us comments. The full edition of the book will be available from Springer, in which we will acknowledge the help we have received from everyone

Cold and Ultracold Molecules: Science, Technology, and Applications

Carr, Lincoln D.; DeMille, David; Krems, Roman V.; Ye, Jun
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/04/2009
Relevância na Pesquisa
55.45%
This article presents a review of the current state of the art in the research field of cold and ultracold molecules. It serves as an introduction to the Special Issue of the New Journal of Physics on Cold and Ultracold Molecules and describes new prospects for fundamental research and technological development. Cold and ultracold molecules may revolutionize physical chemistry and few body physics, provide techniques for probing new states of quantum matter, allow for precision measurements of both fundamental and applied interest, and enable quantum simulations of condensed-matter phenomena. Ultracold molecules offer promising applications such as new platforms for quantum computing, precise control of molecular dynamics, nanolithography, and Bose-enhanced chemistry. The discussion is based on recent experimental and theoretical work and concludes with a summary of anticipated future directions and open questions in this rapidly expanding research field.; Comment: 82 pages, 9 figures, review article to appear in New Journal of Physics Special Issue on Cold and Ultracold Molecules

Characterizing Structure Through Shape Matching and Applications to Self Assembly

Keys, Aaron S.; Iacovella, Christopher R.; Glotzer, Sharon C.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/12/2010
Relevância na Pesquisa
55.57%
Structural quantities such as order parameters and correlation functions are often employed to gain insight into the physical behavior and properties of condensed matter systems. While standard quantities for characterizing structure exist, often they are insufficient for treating problems in the emerging field of nano and microscale self-assembly, where the structures encountered may be complex and unusual. The computer science field of "shape matching" offers a robust solution to this problem by defining diverse methods for quantifying the similarity between arbitrarily complex shapes. Most order parameters and correlation functions used in condensed matter apply a specific measure of structural similarity within the context of a broader scheme. By substituting shape matching quantities for traditional quantities, we retain the essence of the broader scheme, but extend its applicability to more complex structures. Here we review some standard shape matching techniques and discuss how they might be used to create highly flexible structural metrics for diverse systems such as self-assembled matter. We provide three proof-of-concept example problems applying shape matching methods to identifying local and global structures, and tracking structural transitions in complex assembled systems. The shape matching methods reviewed here are applicable to a wide range of condensed matter systems...

Harmonic Order Parameters for Characterizing Complex Particle Morphologies

Keys, Aaron S.; Iacovella, Christopher R.; Glotzer, Sharon C.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/12/2010
Relevância na Pesquisa
55.51%
Order parameters based on spherical harmonics and Fourier coefficients already play a significant role in condensed matter research in the context of systems of spherical or point particles. Here, we extend these types of order parameter to more complex shapes, such as those encountered in nanoscale self-assembly applications. To do so, we build on a powerful set of techniques that originate in the computer science field of "shape matching." We demonstrate how shape matching techniques can be applied to identify unknown structures and create highly-specialized \textit{ad hoc} order parameters. Additionally, we investigate the special symmetry properties of harmonic descriptors, and demonstrate how they can be exploited to provide optimal solutions to certain classes of problems. Our techniques can be applied to particle systems in general, both simulated and experimental, provided the particle positions are known.; Comment: 13 pages, 9 figures, J. Chem. Phys., submitted

Quantum Hamiltonian Complexity

Gharibian, Sevag; Huang, Yichen; Landau, Zeph; Shin, Seung Woo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.55%
We survey the growing field of Quantum Hamiltonian Complexity, which includes the study of Quantum Constraint Satisfaction. In particular, our aim is to provide a computer science-oriented introduction to the subject in order to help bridge the language barrier between computer scientists and physicists in the field. As such, we include the following in this paper: (1) The motivations and history of the field, (2) a glossary of condensed matter physics terms explained in computer-science friendly language, (3) overviews of central ideas from condensed matter physics, such as indistinguishable particles, mean field theory, tensor networks, and area laws, and (4) brief expositions of selected computer science-based results in the area. For example, as part of the latter, we provide a novel information theoretic presentation of Bravyi's polynomial time algorithm for Quantum 2-SAT.; Comment: v3 is identical to v2; simply added new author (S. W. Shin) to arXiv metadata. Comments otherwise identical to v2: 58 pages. Substantial changes: (1) Length almost doubled via addition of sections on physics motivations, indistinguishable particles (i.e. bosons, fermions), area laws, etc. (2) Added new author, S. W. Shin. Minor changes to improve readability throughout

Comment on "Control of Spin Precession in a Spin-Injected Field Effect Transistor" [Science, 325, 1515 (2009)]

Bandyopadhyay, Supriyo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/11/2009
Relevância na Pesquisa
45.53%
A recently published report in the journal Science claims that the Datta-Das Spin Field Effect Transistor has been demonstrated because an exact agreement was found between the voltage modulation in a fabricated structure and a theoretical equation that supposedly describes the voltage modulation of the Datta-Das Transistor. Here, I show that the said theoretical equation holds only for a one-dimensional transistor, or perhaps a quasi one-dimensional transistor, and is certainly not applicable to the two-dimensional transistor studied. Hence, the exact agreement is meaningless and does not substantiate the claim.; Comment: rejected by Science

How to model macroscopic worlds: Towards the philosophy of condensed matter physics.

Yi, Sang Wook
Fonte: London School of Economics and Political Science Thesis Publicador: London School of Economics and Political Science Thesis
Tipo: Thesis; NonPeerReviewed Formato: application/pdf
Publicado em //2001 EN
Relevância na Pesquisa
55.55%
Condensed matter physics studies many-body phenomena, the phenomena involving a huge number of constituents interacting with each other strongly. My theme is modelling in condensed matter physics: the construction of mathematical/physical structures in order to understand many-body phenomena in the world. I study how condensed matter physicists learn about many-body phenomena from the successful employment of models. My proposal is to construe condensed matter physics as engaged essentially with the three activities: model-building, model-exploring and model-based understanding. General theories such as statistical mechanics guide the process of model-building as model-building methodology. I discuss the multiple layers of interactions among general theories (particularly among thermodynamics and statistical mechanics) and show that complementation and cooperation rather than reduction are better concepts for understanding their relation. In model-exploring stage, we probe a model in order to determine what exactly the model implies in itself and what it could with additional constraints. I investigate a number of epistemic roles of approximations in this stage. I also discuss what consists of model-based understanding. With the help of appropriate interpretative models...