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3-Fermion Topological Quantum Computation [1]
3-Fermion topological quantum computation [1] Sam Roberts1 and Dominic J. Williamson2 1Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia 2Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305, USA I. INTRODUCTION Topological quantum computation (TQC) is currently the most promising approach to scalable, fault-tolerant quantum computation. In recent years, the focus has been on TQC with Kitaev's toric code [2], due to it's high threshold to noise [3, 4], and amenability to planar architectures with nearest neighbour interactions. To encode and manipulate quantum information in the toric code, a variety of techniques drawn from condensed matter contexts have been utilised. In particular, some of the efficient approaches for TQC with the toric code rely on creating and manipulating gapped-boundaries, symmetry defects and anyons of the underlying topological phase of matter [5{ 10]. Despite great advances, the overheads for universal fault-tolerant quantum computation remain a formidable challenge. It is therefore important to analyse the potential of TQC in a broad range of topological phases of matter, and attempt to find new computational substrates that require fewer quantum resources to execute fault-tolerant quantum computation. In this work we present an approach to TQC for more general anyon theories based on the Walker{Wang mod- els [11]. This provides a rich class of spin-lattice models in three-dimensions whose boundaries can naturally be used to topologically encode quantum information. The two-dimensional boundary phases of Walker{Wang models accommodate a richer set of possibilities than stand-alone two-dimensional topological phases realized by commuting projector codes [12, 13]. -
Tōhoku Rick Jardine
INFERENCE / Vol. 1, No. 3 Tōhoku Rick Jardine he publication of Alexander Grothendieck’s learning led to great advances: the axiomatic description paper, “Sur quelques points d’algèbre homo- of homology theory, the theory of adjoint functors, and, of logique” (Some Aspects of Homological Algebra), course, the concepts introduced in Tōhoku.5 Tin the 1957 number of the Tōhoku Mathematical Journal, This great paper has elicited much by way of commen- was a turning point in homological algebra, algebraic tary, but Grothendieck’s motivations in writing it remain topology and algebraic geometry.1 The paper introduced obscure. In a letter to Serre, he wrote that he was making a ideas that are now fundamental; its language has with- systematic review of his thoughts on homological algebra.6 stood the test of time. It is still widely read today for the He did not say why, but the context suggests that he was clarity of its ideas and proofs. Mathematicians refer to it thinking about sheaf cohomology. He may have been think- simply as the Tōhoku paper. ing as he did, because he could. This is how many research One word is almost always enough—Tōhoku. projects in mathematics begin. The radical change in Gro- Grothendieck’s doctoral thesis was, by way of contrast, thendieck’s interests was best explained by Colin McLarty, on functional analysis.2 The thesis contained important who suggested that in 1953 or so, Serre inveigled Gro- results on the tensor products of topological vector spaces, thendieck into working on the Weil conjectures.7 The Weil and introduced mathematicians to the theory of nuclear conjectures were certainly well known within the Paris spaces. -
Arxiv:1705.01740V1 [Cond-Mat.Str-El] 4 May 2017 2
Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections M. Hermanns1, I. Kimchi2, J. Knolle3 1Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany 2Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA and 3T.C.M. group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom Quantum spin liquids have fascinated condensed matter physicists for decades because of their unusual properties such as spin fractionalization and long-range entanglement. Unlike conventional symmetry breaking the topological order underlying quantum spin liquids is hard to detect exper- imentally. Even theoretical models are scarce for which the ground state is established to be a quantum spin liquid. The Kitaev honeycomb model and its generalizations to other tri-coordinated lattices are chief counterexamples | they are exactly solvable, harbor a variety of quantum spin liquid phases, and are also relevant for certain transition metal compounds including the polymorphs of (Na,Li)2IrO3 Iridates and RuCl3. In this review, we give an overview of the rich physics of the Kitaev model, including 2D and 3D fractionalization as well as dynamical correlations and behavior at finite temperatures. We discuss the different materials, and argue how the Kitaev model physics can be relevant even though most materials show magnetic ordering at low temperatures. arXiv:1705.01740v1 [cond-mat.str-el] 4 May 2017 2 CONTENTS I. Introduction 2 II. Kitaev quantum spin liquids 3 A. The Kitaev model 3 B. Classifying Kitaev quantum spin liquids by projective symmetries 4 C. Confinement and finite temperature 5 III. Symmetry and chemistry of the Kitaev exchange 6 IV. -
Kitaev Materials
Kitaev Materials Simon Trebst Institute for Theoretical Physics University of Cologne, 50937 Cologne, Germany Contents 1 Spin-orbit entangled Mott insulators 2 1.1 Bond-directional interactions . 4 1.2 Kitaev model . 6 2 Honeycomb Kitaev materials 9 2.1 Na2IrO3 ...................................... 9 2.2 ↵-Li2IrO3 ..................................... 10 2.3 ↵-RuCl3 ...................................... 11 3 Triangular Kitaev materials 15 3.1 Ba3IrxTi3 xO9 ................................... 15 − 3.2 Other materials . 17 4 Three-dimensional Kitaev materials 17 4.1 Conceptual overview . 18 4.2 β-Li2IrO3 and γ-Li2IrO3 ............................. 22 4.3 Other materials . 23 5 Outlook 24 arXiv:1701.07056v1 [cond-mat.str-el] 24 Jan 2017 Lecture Notes of the 48th IFF Spring School “Topological Matter – Topological Insulators, Skyrmions and Majoranas” (Forschungszentrum Julich,¨ 2017). All rights reserved. 2 Simon Trebst 1 Spin-orbit entangled Mott insulators Transition-metal oxides with partially filled 4d and 5d shells exhibit an intricate interplay of electronic, spin, and orbital degrees of freedom arising from a largely accidental balance of electronic correlations, spin-orbit entanglement, and crystal-field effects [1]. With different ma- terials exhibiting slight tilts towards one of the three effects, a remarkably broad variety of novel forms of quantum matter can be explored. On the theoretical side, topology is found to play a crucial role in these systems – an observation which, in the weakly correlated regime, has lead to the discovery of the topological band insulator [2, 3] and subsequently its metallic cousin, the Weyl semi-metal [4, 5]. Upon increasing electronic correlations, Mott insulators with unusual local moments such as spin-orbit entangled degrees of freedom can form and whose collective behavior gives rise to unconventional types of magnetism including the formation of quadrupo- lar correlations or the emergence of so-called spin liquid states. -
Pioneers of Representation Theory, by Charles W
BULLETIN (New Series) OF THE AMERICAN MATHEMATICAL SOCIETY Volume 37, Number 3, Pages 359{362 S 0273-0979(00)00867-3 Article electronically published on February 16, 2000 Pioneers of representation theory, by Charles W. Curtis, Amer. Math. Soc., Prov- idence, RI, 1999, xvi + 287 pp., $49.00, ISBN 0-8218-9002-6 The theory of linear representations of finite groups emerged in a series of papers by Frobenius appearing in 1896{97. This was at first couched in the language of characters but soon evolved into the formulation now considered standard, in which characters give the traces of representing linear transformations. There were of course antecedents in the number-theoretic work of Lagrange, Gauss, and others| especially Dedekind, whose correspondence with Frobenius suggested a way to move from characters of abelian groups to characters of arbitrary finite groups. In the past century this theory has developed in many interesting directions. Besides being a natural tool in the study of the structure of finite groups, it has turned up in many branches of mathematics and has found extensive applications in chemistry and physics. Marking the end of the first century of the subject, the book under review offers a somewhat unusual blend of history, biography, and mathematical exposition. Before discussing the book itself, it may be worthwhile to pose a general question: Does one need to know anything about the history of mathematics (or the lives of individual mathematicians) in order to appreciate the subject matter? Most of us are complacent about quoting the usual sloppy misattributions of famous theorems, even if we are finicky about the details of proofs. -
Some Comments on Physical Mathematics
Preprint typeset in JHEP style - HYPER VERSION Some Comments on Physical Mathematics Gregory W. Moore Abstract: These are some thoughts that accompany a talk delivered at the APS Savannah meeting, April 5, 2014. I have serious doubts about whether I deserve to be awarded the 2014 Heineman Prize. Nevertheless, I thank the APS and the selection committee for their recognition of the work I have been involved in, as well as the Heineman Foundation for its continued support of Mathematical Physics. Above all, I thank my many excellent collaborators and teachers for making possible my participation in some very rewarding scientific research. 1 I have been asked to give a talk in this prize session, and so I will use the occasion to say a few words about Mathematical Physics, and its relation to the sub-discipline of Physical Mathematics. I will also comment on how some of the work mentioned in the citation illuminates this emergent field. I will begin by framing the remarks in a much broader historical and philosophical context. I hasten to add that I am neither a historian nor a philosopher of science, as will become immediately obvious to any expert, but my impression is that if we look back to the modern era of science then major figures such as Galileo, Kepler, Leibniz, and New- ton were neither physicists nor mathematicans. Rather they were Natural Philosophers. Even around the turn of the 19th century the same could still be said of Bernoulli, Euler, Lagrange, and Hamilton. But a real divide between Mathematics and Physics began to open up in the 19th century. -
Mathematicians Fleeing from Nazi Germany
Mathematicians Fleeing from Nazi Germany Mathematicians Fleeing from Nazi Germany Individual Fates and Global Impact Reinhard Siegmund-Schultze princeton university press princeton and oxford Copyright 2009 © by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TW All Rights Reserved Library of Congress Cataloging-in-Publication Data Siegmund-Schultze, R. (Reinhard) Mathematicians fleeing from Nazi Germany: individual fates and global impact / Reinhard Siegmund-Schultze. p. cm. Includes bibliographical references and index. ISBN 978-0-691-12593-0 (cloth) — ISBN 978-0-691-14041-4 (pbk.) 1. Mathematicians—Germany—History—20th century. 2. Mathematicians— United States—History—20th century. 3. Mathematicians—Germany—Biography. 4. Mathematicians—United States—Biography. 5. World War, 1939–1945— Refuges—Germany. 6. Germany—Emigration and immigration—History—1933–1945. 7. Germans—United States—History—20th century. 8. Immigrants—United States—History—20th century. 9. Mathematics—Germany—History—20th century. 10. Mathematics—United States—History—20th century. I. Title. QA27.G4S53 2008 510.09'04—dc22 2008048855 British Library Cataloging-in-Publication Data is available This book has been composed in Sabon Printed on acid-free paper. ∞ press.princeton.edu Printed in the United States of America 10 987654321 Contents List of Figures and Tables xiii Preface xvii Chapter 1 The Terms “German-Speaking Mathematician,” “Forced,” and“Voluntary Emigration” 1 Chapter 2 The Notion of “Mathematician” Plus Quantitative Figures on Persecution 13 Chapter 3 Early Emigration 30 3.1. The Push-Factor 32 3.2. The Pull-Factor 36 3.D. -
January 2011 Prizes and Awards
January 2011 Prizes and Awards 4:25 P.M., Friday, January 7, 2011 PROGRAM SUMMARY OF AWARDS OPENING REMARKS FOR AMS George E. Andrews, President BÔCHER MEMORIAL PRIZE: ASAF NAOR, GUNTHER UHLMANN American Mathematical Society FRANK NELSON COLE PRIZE IN NUMBER THEORY: CHANDRASHEKHAR KHARE AND DEBORAH AND FRANKLIN TEPPER HAIMO AWARDS FOR DISTINGUISHED COLLEGE OR UNIVERSITY JEAN-PIERRE WINTENBERGER TEACHING OF MATHEMATICS LEVI L. CONANT PRIZE: DAVID VOGAN Mathematical Association of America JOSEPH L. DOOB PRIZE: PETER KRONHEIMER AND TOMASZ MROWKA EULER BOOK PRIZE LEONARD EISENBUD PRIZE FOR MATHEMATICS AND PHYSICS: HERBERT SPOHN Mathematical Association of America RUTH LYTTLE SATTER PRIZE IN MATHEMATICS: AMIE WILKINSON DAVID P. R OBBINS PRIZE LEROY P. S TEELE PRIZE FOR LIFETIME ACHIEVEMENT: JOHN WILLARD MILNOR Mathematical Association of America LEROY P. S TEELE PRIZE FOR MATHEMATICAL EXPOSITION: HENRYK IWANIEC BÔCHER MEMORIAL PRIZE LEROY P. S TEELE PRIZE FOR SEMINAL CONTRIBUTION TO RESEARCH: INGRID DAUBECHIES American Mathematical Society FOR AMS-MAA-SIAM LEVI L. CONANT PRIZE American Mathematical Society FRANK AND BRENNIE MORGAN PRIZE FOR OUTSTANDING RESEARCH IN MATHEMATICS BY AN UNDERGRADUATE STUDENT: MARIA MONKS LEONARD EISENBUD PRIZE FOR MATHEMATICS AND OR PHYSICS F AWM American Mathematical Society LOUISE HAY AWARD FOR CONTRIBUTIONS TO MATHEMATICS EDUCATION: PATRICIA CAMPBELL RUTH LYTTLE SATTER PRIZE IN MATHEMATICS M. GWENETH HUMPHREYS AWARD FOR MENTORSHIP OF UNDERGRADUATE WOMEN IN MATHEMATICS: American Mathematical Society RHONDA HUGHES ALICE T. S CHAFER PRIZE FOR EXCELLENCE IN MATHEMATICS BY AN UNDERGRADUATE WOMAN: LOUISE HAY AWARD FOR CONTRIBUTIONS TO MATHEMATICS EDUCATION SHERRY GONG Association for Women in Mathematics ALICE T. S CHAFER PRIZE FOR EXCELLENCE IN MATHEMATICS BY AN UNDERGRADUATE WOMAN FOR JPBM Association for Women in Mathematics COMMUNICATIONS AWARD: NICOLAS FALACCI AND CHERYL HEUTON M. -
Manifolds at and Beyond the Limit of Metrisability 1 Introduction
ISSN 1464-8997 125 Geometry & Topology Monographs Volume 2: Proceedings of the Kirbyfest Pages 125–133 Manifolds at and beyond the limit of metrisability David Gauld Abstract In this paper we give a brief introduction to criteria for metris- ability of a manifold and to some aspects of non-metrisable manifolds. Bias towards work currently being done by the author and his colleagues at the University of Auckland will be very evident. Wishing Robion Kirby a happy sixtieth with many more to follow. AMS Classification 57N05, 57N15; 54E35 Keywords Metrisability, non-metrisable manifold 1 Introduction By a manifold we mean a connected, Hausdorff topological space in which each point has a neighbourhood homeomorphic to some euclidean space Rn .Thus we exclude boundaries. Although the manifolds considered here tend, in a sense, to be large, it is straightforward to show that any finite set of points in a manifold lies in an open subset homeomorphic to Rn ; in particular each finite set lies in an arc. Set Theory plays a major role in the study of large manifolds; indeed, it is often the case that the answer to a particular problem depends on the Set Theory involved. On the other hand Algebraic Topology seems to be of less use, at least so far, with [16, Section 5] and [5] being among the few examples. Perhaps it is not surprising that Set Theory is of major use while Algebraic Topology is of minor use given that the former is of greater significance when the size of the sets involved grows, while the latter is most effective when we are dealing with compact sets. -
Math 126 Lecture 4. Basic Facts in Representation Theory
Math 126 Lecture 4. Basic facts in representation theory. Notice. Definition of a representation of a group. The theory of group representations is the creation of Frobenius: Georg Frobenius lived from 1849 to 1917 Frobenius combined results from the theory of algebraic equations, geometry, and number theory, which led him to the study of abstract groups, the representation theory of groups and the character theory of groups. Find out more at: http://www-history.mcs.st-andrews.ac.uk/history/ Mathematicians/Frobenius.html Matrix form of a representation. Equivalence of two representations. Invariant subspaces. Irreducible representations. One dimensional representations. Representations of cyclic groups. Direct sums. Tensor product. Unitary representations. Averaging over the group. Maschke’s theorem. Heinrich Maschke 1853 - 1908 Schur’s lemma. Issai Schur Biography of Schur. Issai Schur Born: 10 Jan 1875 in Mogilyov, Mogilyov province, Russian Empire (now Belarus) Died: 10 Jan 1941 in Tel Aviv, Palestine (now Israel) Although Issai Schur was born in Mogilyov on the Dnieper, he spoke German without a trace of an accent, and nobody even guessed that it was not his first language. He went to Latvia at the age of 13 and there he attended the Gymnasium in Libau, now called Liepaja. In 1894 Schur entered the University of Berlin to read mathematics and physics. Frobenius was one of his teachers and he was to greatly influence Schur and later to direct his doctoral studies. Frobenius and Burnside had been the two main founders of the theory of representations of groups as groups of matrices. This theory proved a very powerful tool in the study of groups and Schur was to learn the foundations of this subject from Frobenius. -
A Brief History of an Important Classical Theorem
Advances in Group Theory and Applications c 2016 AGTA - www.advgrouptheory.com/journal 2 (2016), pp. 121–124 ISSN: 2499-1287 DOI: 10.4399/97888548970148 A Brief History of an Important Classical Theorem L.A. Kurdachenko — I.Ya.Subbotin (Received Nov. 6, 2016 – Communicated by Francesco de Giovanni) Mathematics Subject Classification (2010): 20F14, 20F19 Keywords: Schur theorem; Baer theorem; Neumann theorem This note is a by-product of the authors’ investigation of relations between the lower and upper central series in a group. There are some famous theorems laid at the foundation of any research in this area. These theorems are so well-known that, by the established tra- dition, they usually were named in honor of the mathematicians who first formulated and proved them. However, this did not always hap- pened. Our intention here is to talk about one among the fundamen- tal results of infinite group theory which is linked to Issai Schur. Issai Schur (January 10, 1875 in Mogilev, Belarus — January 10, 1941 in Tel Aviv, Israel) was a very famous mathematician who proved many important and interesting results, first in algebra and number theory. There is a biography sketch of I. Schur wonderfully written by J.J. O’Connor and E.F. Robertson [6]. The authors documented that I. Schur actively and successfully worked in many branches of mathematics, such as for example, finite groups, matrices, alge- braic equations (where he gave examples of equations with alterna- ting Galois groups), number theory, divergent series, integral equa- tions, function theory. We cannot add anything important to this, saturated with factual and emotional details, article of O’Connor 122 L.A. -
Man and Machine Thinking About the Smooth 4-Dimensional Poincaré
Quantum Topology 1 (2010), xxx{xxx Quantum Topology c European Mathematical Society Man and machine thinking about the smooth 4-dimensional Poincar´econjecture. Michael Freedman, Robert Gompf, Scott Morrison and Kevin Walker Mathematics Subject Classification (2000).57R60 ; 57N13; 57M25 Keywords.Property R, Cappell-Shaneson spheres, Khovanov homology, s-invariant, Poincar´e conjecture Abstract. While topologists have had possession of possible counterexamples to the smooth 4-dimensional Poincar´econjecture (SPC4) for over 30 years, until recently no invariant has existed which could potentially distinguish these examples from the standard 4-sphere. Rasmussen's s- invariant, a slice obstruction within the general framework of Khovanov homology, changes this state of affairs. We studied a class of knots K for which nonzero s(K) would yield a counterexample to SPC4. Computations are extremely costly and we had only completed two tests for those K, with the computations showing that s was 0, when a landmark posting of Akbulut [3] altered the terrain. His posting, appearing only six days after our initial posting, proved that the family of \Cappell{Shaneson" homotopy spheres that we had geared up to study were in fact all standard. The method we describe remains viable but will have to be applied to other examples. Akbulut's work makes SPC4 seem more plausible, and in another section of this paper we explain that SPC4 is equivalent to an appropriate generalization of Property R (\in S3, only an unknot can yield S1 × S2 under surgery"). We hope that this observation, and the rich relations between Property R and ideas such as taut foliations, contact geometry, and Heegaard Floer homology, will encourage 3-manifold topologists to look at SPC4.