The Physics of Computing

Description

This book presents a self-contained introduction to the physics of computing, by addressing the fundamental underlying principles that involve the act of computing, regardless of the actual machine that is used to compute. Questions like “what is the minimum energy required to perform a computation?”, “what is the ultimate computational speed that a computer can achieve?” or “how long can a memory last”, are addressed here, starting from basic physics principles. The book is intended for physicists, engineers, and computer scientists, and it is designed for self-study by researchers who want to enter the field or as the main text for a one semester course at advanced undergraduate or graduate level. The theoretical concepts presented in this book are systematically developed from the very beginning, which only requires basic knowledge in physics and mathematics. Preface Acknowledgements Contents 1 Computing with Devices 1.1 What Do We Mean with Computing? 1.2 Calculus Means Stone 1.3 On Computing Devices 1.4 Universal Machines 1.5 Interesting Questions References 2 The Physics of Digital Computing 2.1 Digits 2.2 Binary Digits 2.3 Binary Switches 2.4 Logic Switches 2.5 Logic Gates 2.6 Logic Gates Made by Logic Switches 2.7 A Dynamical Model 2.8 The Switch References 3 What is Friction 3.1 Energy Conservation 3.2 Brownian Motion 3.3 Langevin’s Approach 3.4 Fluctuating Cantilever 3.5 Fluctuation and Dissipation Come Together 3.6 Thermodynamics for Everybody 3.7 Energy and Entropy at Small Scales 3.8 Friction at Small Scales References 4 The Physics of Small-Scale Switches 4.1 Logic Switches as Thermodynamic Systems 4.2 A Digression: Energy Dissipation is an Illusion? 4.3 The Switch Dynamics in the Presence of Fluctuations 4.4 Combinational Switches: The Switch in the Presence of Fluctuations 4.5 Sequential Switches: The Switch in the Presence of Fluctuations References 5 Fundamental Energy Limits in Computation 5.1 How Much Energy Does It Take to Switch and Why This is Important? 5.2 Combinational Switches: Minimum Dissipated Energy 5.3 Sequential Switches: Minimum Dissipated Energy 5.4 Bit Reset: Minimum Dissipated Energy 5.5 Minimum Dissipated Energy: How Far Are We? References 6 Storing Data 6.1 Memories: How Do They Work? 6.2 Memory Dynamics 6.3 Fundamental Energy Limits for Memory Storage 6.4 Fundamental Limits for Memory Preservation 6.5 Beyond Digital Memories References 7 What About Information? 7.1 The Big Picture 7.2 Information: What is It? 7.3 Landauer’s Principle: Long Story Short 7.4 Sub-kBT Microelectromechanical Irreversible OR Logic Gate References 8 Cloud Computing and Data Transmission 8.1 A New Name for an Old Situation 8.2 Signal Transmission 8.3 Minimum Energy for Transmitting One Bit Reference 9 Analog Computing 9.1 What is Analog Computing? 9.2 Analog Computers Came First 9.3 Electronic Analog Computers 9.4 Energy Dissipation and Entropy Reduction in Analog Computing References 10 Computing in the Quantum Regime 10.1 How is Quantum Computing Different from Classical Computing 10.2 Quantum Computation and Energy Dissipation 10.3 Quantum Binary Switches 10.4 Quantum Limit in Computing Speed 10.5 Quantum Limit to Entropy Reduction in Analog Computing Systems References 11 The Future of Computing and Society 11.1 Reflections on the Computing Era 11.2 From the Introduction of Digital Technology to Big Data 11.3 Big Data and AI for the Creation of New Knowledge 11.4 The Surveillance Society Nightmare 11.5 Are Digital Data Inevitable? 11.6 Computers of the Future: The Atoms Strike Back References