Emerging Insights on Limitations of Quantum Computing Shape Quest for Fast Algorithms
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Multiplicative Weights Update Method: a Meta-Algorithm and Applications
THEORY OF COMPUTING, Volume 8 (2012), pp. 121–164 www.theoryofcomputing.org RESEARCH SURVEY The Multiplicative Weights Update Method: A Meta-Algorithm and Applications Sanjeev Arora∗ Elad Hazan Satyen Kale Received: July 22, 2008; revised: July 2, 2011; published: May 1, 2012. Abstract: Algorithms in varied fields use the idea of maintaining a distribution over a certain set and use the multiplicative update rule to iteratively change these weights. Their analyses are usually very similar and rely on an exponential potential function. In this survey we present a simple meta-algorithm that unifies many of these disparate algorithms and derives them as simple instantiations of the meta-algorithm. We feel that since this meta-algorithm and its analysis are so simple, and its applications so broad, it should be a standard part of algorithms courses, like “divide and conquer.” ACM Classification: G.1.6 AMS Classification: 68Q25 Key words and phrases: algorithms, game theory, machine learning 1 Introduction The Multiplicative Weights (MW) method is a simple idea which has been repeatedly discovered in fields as diverse as Machine Learning, Optimization, and Game Theory. The setting for this algorithm is the following. A decision maker has a choice of n decisions, and needs to repeatedly make a decision and obtain an associated payoff. The decision maker’s goal, in the long run, is to achieve a total payoff which is comparable to the payoff of that fixed decision that maximizes the total payoff with the benefit of ∗This project was supported by David and Lucile Packard Fellowship and NSF grants MSPA-MCS 0528414 and CCR- 0205594. -
Limits on Efficient Computation in the Physical World
Limits on Efficient Computation in the Physical World by Scott Joel Aaronson Bachelor of Science (Cornell University) 2000 A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Computer Science in the GRADUATE DIVISION of the UNIVERSITY of CALIFORNIA, BERKELEY Committee in charge: Professor Umesh Vazirani, Chair Professor Luca Trevisan Professor K. Birgitta Whaley Fall 2004 The dissertation of Scott Joel Aaronson is approved: Chair Date Date Date University of California, Berkeley Fall 2004 Limits on Efficient Computation in the Physical World Copyright 2004 by Scott Joel Aaronson 1 Abstract Limits on Efficient Computation in the Physical World by Scott Joel Aaronson Doctor of Philosophy in Computer Science University of California, Berkeley Professor Umesh Vazirani, Chair More than a speculative technology, quantum computing seems to challenge our most basic intuitions about how the physical world should behave. In this thesis I show that, while some intuitions from classical computer science must be jettisoned in the light of modern physics, many others emerge nearly unscathed; and I use powerful tools from computational complexity theory to help determine which are which. In the first part of the thesis, I attack the common belief that quantum computing resembles classical exponential parallelism, by showing that quantum computers would face serious limitations on a wider range of problems than was previously known. In partic- ular, any quantum algorithm that solves the collision problem—that of deciding whether a sequence of n integers is one-to-one or two-to-one—must query the sequence Ω n1/5 times. -
Four Results of Jon Kleinberg a Talk for St.Petersburg Mathematical Society
Four Results of Jon Kleinberg A Talk for St.Petersburg Mathematical Society Yury Lifshits Steklov Institute of Mathematics at St.Petersburg May 2007 1 / 43 2 Hubs and Authorities 3 Nearest Neighbors: Faster Than Brute Force 4 Navigation in a Small World 5 Bursty Structure in Streams Outline 1 Nevanlinna Prize for Jon Kleinberg History of Nevanlinna Prize Who is Jon Kleinberg 2 / 43 3 Nearest Neighbors: Faster Than Brute Force 4 Navigation in a Small World 5 Bursty Structure in Streams Outline 1 Nevanlinna Prize for Jon Kleinberg History of Nevanlinna Prize Who is Jon Kleinberg 2 Hubs and Authorities 2 / 43 4 Navigation in a Small World 5 Bursty Structure in Streams Outline 1 Nevanlinna Prize for Jon Kleinberg History of Nevanlinna Prize Who is Jon Kleinberg 2 Hubs and Authorities 3 Nearest Neighbors: Faster Than Brute Force 2 / 43 5 Bursty Structure in Streams Outline 1 Nevanlinna Prize for Jon Kleinberg History of Nevanlinna Prize Who is Jon Kleinberg 2 Hubs and Authorities 3 Nearest Neighbors: Faster Than Brute Force 4 Navigation in a Small World 2 / 43 Outline 1 Nevanlinna Prize for Jon Kleinberg History of Nevanlinna Prize Who is Jon Kleinberg 2 Hubs and Authorities 3 Nearest Neighbors: Faster Than Brute Force 4 Navigation in a Small World 5 Bursty Structure in Streams 2 / 43 Part I History of Nevanlinna Prize Career of Jon Kleinberg 3 / 43 Nevanlinna Prize The Rolf Nevanlinna Prize is awarded once every 4 years at the International Congress of Mathematicians, for outstanding contributions in Mathematical Aspects of Information Sciences including: 1 All mathematical aspects of computer science, including complexity theory, logic of programming languages, analysis of algorithms, cryptography, computer vision, pattern recognition, information processing and modelling of intelligence. -
Navigability of Small World Networks
Navigability of Small World Networks Pierre Fraigniaud CNRS and University Paris Sud http://www.lri.fr/~pierre Introduction Interaction Networks • Communication networks – Internet – Ad hoc and sensor networks • Societal networks – The Web – P2P networks (the unstructured ones) • Social network – Acquaintance – Mail exchanges • Biology (Interactome network), linguistics, etc. Dec. 19, 2006 HiPC'06 3 Common statistical properties • Low density • “Small world” properties: – Average distance between two nodes is small, typically O(log n) – The probability p that two distinct neighbors u1 and u2 of a same node v are neighbors is large. p = clustering coefficient • “Scale free” properties: – Heavy tailed probability distributions (e.g., of the degrees) Dec. 19, 2006 HiPC'06 4 Gaussian vs. Heavy tail Example : human sizes Example : salaries µ Dec. 19, 2006 HiPC'06 5 Power law loglog ppk prob{prob{ X=kX=k }} ≈≈ kk-α loglog kk Dec. 19, 2006 HiPC'06 6 Random graphs vs. Interaction networks • Random graphs: prob{e exists} ≈ log(n)/n – low clustering coefficient – Gaussian distribution of the degrees • Interaction networks – High clustering coefficient – Heavy tailed distribution of the degrees Dec. 19, 2006 HiPC'06 7 New problematic • Why these networks share these properties? • What model for – Performance analysis of these networks – Algorithm design for these networks • Impact of the measures? • This lecture addresses navigability Dec. 19, 2006 HiPC'06 8 Navigability Milgram Experiment • Source person s (e.g., in Wichita) • Target person t (e.g., in Cambridge) – Name, professional occupation, city of living, etc. • Letter transmitted via a chain of individuals related on a personal basis • Result: “six degrees of separation” Dec. -
A Decade of Lattice Cryptography
Full text available at: http://dx.doi.org/10.1561/0400000074 A Decade of Lattice Cryptography Chris Peikert Computer Science and Engineering University of Michigan, United States Boston — Delft Full text available at: http://dx.doi.org/10.1561/0400000074 Foundations and Trends R in Theoretical Computer Science Published, sold and distributed by: now Publishers Inc. PO Box 1024 Hanover, MA 02339 United States Tel. +1-781-985-4510 www.nowpublishers.com [email protected] Outside North America: now Publishers Inc. PO Box 179 2600 AD Delft The Netherlands Tel. +31-6-51115274 The preferred citation for this publication is C. Peikert. A Decade of Lattice Cryptography. Foundations and Trends R in Theoretical Computer Science, vol. 10, no. 4, pp. 283–424, 2014. R This Foundations and Trends issue was typeset in LATEX using a class file designed by Neal Parikh. Printed on acid-free paper. ISBN: 978-1-68083-113-9 c 2016 C. Peikert All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, mechanical, photocopying, recording or otherwise, without prior written permission of the publishers. Photocopying. In the USA: This journal is registered at the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923. Authorization to photocopy items for in- ternal or personal use, or the internal or personal use of specific clients, is granted by now Publishers Inc for users registered with the Copyright Clearance Center (CCC). The ‘services’ for users can be found on the internet at: www.copyright.com For those organizations that have been granted a photocopy license, a separate system of payment has been arranged. -
Expander Flows, Geometric Embeddings and Graph Partitioning
Expander Flows, Geometric Embeddings and Graph Partitioning SANJEEV ARORA Princeton University SATISH RAO and UMESH VAZIRANI UC Berkeley We give a O(√log n)-approximation algorithm for the sparsest cut, edge expansion, balanced separator,andgraph conductance problems. This improves the O(log n)-approximation of Leighton and Rao (1988). We use a well-known semidefinite relaxation with triangle inequality constraints. Central to our analysis is a geometric theorem about projections of point sets in d, whose proof makes essential use of a phenomenon called measure concentration. We also describe an interesting and natural “approximate certificate” for a graph’s expansion, which involves embedding an n-node expander in it with appropriate dilation and congestion. We call this an expander flow. Categories and Subject Descriptors: F.2.2 [Theory of Computation]: Analysis of Algorithms and Problem Complexity; G.2.2 [Mathematics of Computing]: Discrete Mathematics and Graph Algorithms General Terms: Algorithms,Theory Additional Key Words and Phrases: Graph Partitioning,semidefinite programs,graph separa- tors,multicommodity flows,expansion,expanders 1. INTRODUCTION Partitioning a graph into two (or more) large pieces while minimizing the size of the “interface” between them is a fundamental combinatorial problem. Graph partitions or separators are central objects of study in the theory of Markov chains, geometric embeddings and are a natural algorithmic primitive in numerous settings, including clustering, divide and conquer approaches, PRAM emulation, VLSI layout, and packet routing in distributed networks. Since finding optimal separators is NP-hard, one is forced to settle for approximation algorithms (see Shmoys [1995]). Here we give new approximation algorithms for some of the important problems in this class. -
Constraint Based Dimension Correlation and Distance
Preface The papers in this volume were presented at the Fourteenth Annual IEEE Conference on Computational Complexity held from May 4-6, 1999 in Atlanta, Georgia, in conjunction with the Federated Computing Research Conference. This conference was sponsored by the IEEE Computer Society Technical Committee on Mathematical Foundations of Computing, in cooperation with the ACM SIGACT (The special interest group on Algorithms and Complexity Theory) and EATCS (The European Association for Theoretical Computer Science). The call for papers sought original research papers in all areas of computational complexity. A total of 70 papers were submitted for consideration of which 28 papers were accepted for the conference and for inclusion in these proceedings. Six of these papers were accepted to a joint STOC/Complexity session. For these papers the full conference paper appears in the STOC proceedings and a one-page summary appears in these proceedings. The program committee invited two distinguished researchers in computational complexity - Avi Wigderson and Jin-Yi Cai - to present invited talks. These proceedings contain survey articles based on their talks. The program committee thanks Pradyut Shah and Marcus Schaefer for their organizational and computer help, Steve Tate and the SIGACT Electronic Publishing Board for the use and help of the electronic submissions server, Peter Shor and Mike Saks for the electronic conference meeting software and Danielle Martin of the IEEE for editing this volume. The committee would also like to thank the following people for their help in reviewing the papers: E. Allender, V. Arvind, M. Ajtai, A. Ambainis, G. Barequet, S. Baumer, A. Berthiaume, S. -
Inter Actions Department of Physics 2015
INTER ACTIONS DEPARTMENT OF PHYSICS 2015 The Department of Physics has a very accomplished family of alumni. In this issue we begin to recognize just a few of them with stories submitted by graduates from each of the decades since 1950. We want to invite all of you to renew and strengthen your ties to our department. We would love to hear from you, telling us what you are doing and commenting on how the department has helped in your career and life. Alumna returns to the Physics Department to Implement New MCS Core Education When I heard that the Department of Physics needed a hand implementing the new MCS Core Curriculum, I couldn’t imagine a better fit. Not only did it provide an opportunity to return to my hometown, but Carnegie Mellon itself had been a fixture in my life for many years, from taking classes as a high school student to teaching after graduation. I was thrilled to have the chance to return. I graduated from Carnegie Mellon in 2008, with a B.S. in physics and a B.A. in Japanese. Afterwards, I continued to teach at CMARC’s Summer Academy for Math and Science during the summers while studying down the street at the University of Pittsburgh. In 2010, I earned my M.A. in East Asian Studies there based on my research into how cultural differences between Japan and America have helped shape their respective robotics industries. After receiving my master’s degree and spending a summer studying in Japan, I taught for Kaplan as graduate faculty for a year before joining the Department of Physics at Cornell University. -
Computational Pseudorandomness, the Wormhole Growth Paradox, and Constraints on the Ads/CFT Duality
Computational Pseudorandomness, the Wormhole Growth Paradox, and Constraints on the AdS/CFT Duality Adam Bouland Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, 617 Soda Hall, Berkeley, CA 94720, U.S.A. [email protected] Bill Fefferman Department of Computer Science, University of Chicago, 5730 S Ellis Ave, Chicago, IL 60637, U.S.A. [email protected] Umesh Vazirani Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, 671 Soda Hall, Berkeley, CA 94720, U.S.A. [email protected] Abstract The AdS/CFT correspondence is central to efforts to reconcile gravity and quantum mechanics, a fundamental goal of physics. It posits a duality between a gravitational theory in Anti de Sitter (AdS) space and a quantum mechanical conformal field theory (CFT), embodied in a map known as the AdS/CFT dictionary mapping states to states and operators to operators. This dictionary map is not well understood and has only been computed on special, structured instances. In this work we introduce cryptographic ideas to the study of AdS/CFT, and provide evidence that either the dictionary must be exponentially hard to compute, or else the quantum Extended Church-Turing thesis must be false in quantum gravity. Our argument has its origins in a fundamental paradox in the AdS/CFT correspondence known as the wormhole growth paradox. The paradox is that the CFT is believed to be “scrambling” – i.e. the expectation value of local operators equilibrates in polynomial time – whereas the gravity theory is not, because the interiors of certain black holes known as “wormholes” do not equilibrate and instead their volume grows at a linear rate for at least an exponential amount of time. -
Quantum Computing : a Gentle Introduction / Eleanor Rieffel and Wolfgang Polak
QUANTUM COMPUTING A Gentle Introduction Eleanor Rieffel and Wolfgang Polak The MIT Press Cambridge, Massachusetts London, England ©2011 Massachusetts Institute of Technology All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher. For information about special quantity discounts, please email [email protected] This book was set in Syntax and Times Roman by Westchester Book Group. Printed and bound in the United States of America. Library of Congress Cataloging-in-Publication Data Rieffel, Eleanor, 1965– Quantum computing : a gentle introduction / Eleanor Rieffel and Wolfgang Polak. p. cm.—(Scientific and engineering computation) Includes bibliographical references and index. ISBN 978-0-262-01506-6 (hardcover : alk. paper) 1. Quantum computers. 2. Quantum theory. I. Polak, Wolfgang, 1950– II. Title. QA76.889.R54 2011 004.1—dc22 2010022682 10987654321 Contents Preface xi 1 Introduction 1 I QUANTUM BUILDING BLOCKS 7 2 Single-Qubit Quantum Systems 9 2.1 The Quantum Mechanics of Photon Polarization 9 2.1.1 A Simple Experiment 10 2.1.2 A Quantum Explanation 11 2.2 Single Quantum Bits 13 2.3 Single-Qubit Measurement 16 2.4 A Quantum Key Distribution Protocol 18 2.5 The State Space of a Single-Qubit System 21 2.5.1 Relative Phases versus Global Phases 21 2.5.2 Geometric Views of the State Space of a Single Qubit 23 2.5.3 Comments on General Quantum State Spaces -
The BBVA Foundation Recognizes Charles H. Bennett, Gilles Brassard
www.frontiersofknowledgeawards-fbbva.es Press release 3 March, 2020 The BBVA Foundation recognizes Charles H. Bennett, Gilles Brassard and Peter Shor for their fundamental role in the development of quantum computation and cryptography In the 1980s, chemical physicist Bennett and computer scientist Brassard invented quantum cryptography, a technology that using the laws of quantum physics in a way that makes them unreadable to eavesdroppers, in the words of the award committee The importance of this technology was demonstrated ten years later, when mathematician Shor discovered that a hypothetical quantum computer would drive a hole through the conventional cryptographic systems that underpin the security and privacy of Internet communications Their landmark contributions have boosted the development of quantum computers, which promise to perform calculations at a far greater speed and scale than machines, and enabled cryptographic systems that guarantee the inviolability of communications The BBVA Foundation Frontiers of Knowledge Award in Basic Sciences has gone in this twelfth edition to Charles Bennett, Gilles Brassard and Peter Shor for their outstanding contributions to the field of quantum computation and communication Bennett and Brassard, a chemical physicist and computer scientist respectively, invented quantum cryptography in the 1980s to ensure the physical inviolability of data communications. The importance of their work became apparent ten years later, when mathematician Peter Shor discovered that a hypothetical quantum computer would render effectively useless the communications. The award committee, chaired by Nobel Physics laureate Theodor Hänsch with quantum physicist Ignacio Cirac acting as its secretary, remarked on the leap forward in quantum www.frontiersofknowledgeawards-fbbva.es Press release 3 March, 2020 technologies witnessed in these last few years, an advance which draws heavily on the new . -
Quantum-Proofing the Blockchain
QUANTUM-PROOFING THE BLOCKCHAIN Vlad Gheorghiu, Sergey Gorbunov, Michele Mosca, and Bill Munson University of Waterloo November 2017 A BLOCKCHAIN RESEARCH INSTITUTE BIG IDEA WHITEPAPER Realizing the new promise of the digital economy In 1994, Don Tapscott coined the phrase, “the digital economy,” with his book of that title. It discussed how the Web and the Internet of information would bring important changes in business and society. Today the Internet of value creates profound new possibilities. In 2017, Don and Alex Tapscott launched the Blockchain Research Institute to help realize the new promise of the digital economy. We research the strategic implications of blockchain technology and produce practical insights to contribute global blockchain knowledge and help our members navigate this revolution. Our findings, conclusions, and recommendations are initially proprietary to our members and ultimately released to the public in support of our mission. To find out more, please visitwww.blockchainresearchinstitute.org . Blockchain Research Institute, 2018 Except where otherwise noted, this work is copyrighted 2018 by the Blockchain Research Institute and licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Public License. To view a copy of this license, send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA, or visit creativecommons.org/ licenses/by-nc-nd/4.0/legalcode. This document represents the views of its author(s), not necessarily those of Blockchain Research Institute or the Tapscott Group. This material is for informational purposes only; it is neither investment advice nor managerial consulting. Use of this material does not create or constitute any kind of business relationship with the Blockchain Research Institute or the Tapscott Group, and neither the Blockchain Research Institute nor the Tapscott Group is liable for the actions of persons or organizations relying on this material.