The operation of semiconductor devices depends upon the use of electrical potential barriers (such as gate depletion) in controlling the carrier densities (electrons and holes) and their transport. Although a successful device design is quite complicated and involves many aspects, the device engineering is mostly to devise a "best" device design by defIning optimal device structures and manipulating impurity profIles to obtain optimal control of the carrier flow through the device. This becomes increasingly diffIcult as the device scale becomes smaller and smaller. Since the introduction of integrated circuits, the number of individual transistors on a single chip has doubled approximately every three years. As the number of devices has grown, the critical dimension of the smallest feature, such as a gate length (which is related to the transport length defIning the channel), has consequently declined. The reduction of this design rule proceeds approximately by a factor of 1. 4 each generation, which means we will be using 0. 1-0. 15 ). lm rules for the 4 Gb chips a decade from now. If we continue this extrapolation, current technology will require 30 nm design rules, and a cell 3 2 size

The majority of the chapters in this volume represent a series of lectures. that were given at a workshop on quantum transport in ultrasmall electron devices, held at San Miniato, Italy, in March 1987. These have, of course, been extended and updated during the period that has elapsed since the workshop was held, and have been supplemented with additional chapters devoted to the tunneling process in semiconductor quantum-well structures. The aim of this work is to review and present the current understanding in nonequilibrium quantum transport appropriate to semiconductors. Gen erally, the field of interest can be categorized as that appropriate to inhomogeneous transport in strong applied fields. These fields are most likely to be strongly varying in both space and time. Most of the literature on quantum transport in semiconductors (or in metallic systems, for that matter) is restricted to the equilibrium approach, in which spectral densities are maintained as semiclassical energy conserving delta functions, or perhaps incorporating some form of collision broadening through a Lorentzian shape, and the distribution functions are kept in the equilibrium Fermi-Dirac form. The most familiar field of nonequilibrium transport, at least for the semiconductor world, is that of hot carriers in semiconductors.

This comprehensive textbook provides the fundamental concepts and methods of dissipative quantum mechanics and related issues in condensed matter physics starting from first principles. It deals with the phenomena and theory of decoherence, relaxation and dissipation in quantum mechanics that arise from the random exchange of energy with the environment. Major theoretical advances in combination with stunning experimental achievements and the arising perspective for quantum computing have brightened the field and brought it to the attention of the general community in natural sciences. Expertise in dissipative quantum mechanics is by now beneficial in a broad sphere.This book — originally published in 1992 and republished as enlarged and updated second, third and fourth edition in 1999, 2008, and 2012 — dives even deeper into the fundamental concepts, methods and applications of quantum dissipation. The fifth edition provides a self-contained and updated account of the quantum mechanics and quantum statistics of open systems. The subject matter of the book has been thoroughly revised to better comply with the needs of newcomers and the demands of the advanced readership. Most of the chapters are rewritten to enhance clarity and topicality. Four new chapters covering recent developments in the field have been added. There are about 600 references. This book is intended for use by advanced undergraduate and graduate students in physics, and for researchers active in the field. They will find the monograph as a rich and stimulating source.

Continuing miniaturization of electronic devices, together with the quickly growing number of nanotechnological applications, demands a profound understanding of the underlying physics. Most of the fundamental problems of modern condensed matter physics involve various aspects of quantum transport and fluctuation phenomena at the nanoscale. In nanostructures, electrons are usually confined to a limited volume and interact with each other and lattice ions, simultaneously suffering multiple scattering events on impurities, barriers, surface imperfections, and other defects. Electron interaction with other degrees of freedom generally yields two major consequences, quantum dissipation and quantum decoherence. In other words, electrons can lose their energy and ability for quantum interference even at very low temperatures. These two different, but related, processes are at the heart of all quantum phenomena discussed in this book. This book presents copious details to facilitate the understanding of the basic physics behind a result and the learning to technically reproduce the result without delving into extra literature. The book subtly balances the description of theoretical methods and techniques and the display of the rich landscape of the physical phenomena that can be accessed by these methods. It is useful for a broad readership ranging from master’s and PhD students to postdocs and senior researchers.

This text presents the statistical theory of wave scattering and quantum transport in complex - chaotic and disordered - systems.

Quantum information science is a new field of science and technology which requires the collaboration of researchers coming from different fields of physics, mathematics, and engineering: both theoretical and applied. Quantum Computing and Quantum Bits in Mesoscopic Systems addresses fundamental aspects of quantum physics, enhancing the connection between the quantum behavior of macroscopic systems and information theory. In addition to theoretical quantum physics, the book comprehensively explores practical implementation of quantum computing and information processing devices. On the experimental side, this book reports on recent and previous observations of quantum behavior in several physical systems, coherently coupled Bose-Einstein condensates, quantum dots, superconducting quantum interference devices, Cooper pair boxes, and electron pumps in the context of the Josephson effect. In these systems, the book discusses all required steps, from fabrication through characterization to the final basic implementation for quantum computing.

Quantum information theory has revolutionised our view on the true nature of information and has led to such intriguing topics as teleportation and quantum computation. The field - by its very nature strongly interdisciplinary, with deep roots in the foundations both of quantum mechanics and of information theory and computer science - has become a major subject for scientists working in fields as diverse as quantum optics, superconductivity or information theory, all the way to computer engineers.

Exploiting time-dependent effects to induce and control currents through mesoscopic and nano -scopic conductors is a major challenge in the field of quantum transport. In this dissertation we consider two nanoscale systems in which a current can be induced through intriguing mechanisms of coupling between excitations by external fields and electron transport.We first study a quantum pumping problem, analyzing the possibility to induce a DC response to an AC parametric driving through a three-site system in a ring configuration. We are interested in particular in the crossover between adiabatic and antiadiabatic driving regimes and in the presence of dissipation, which is accounted for by coupling with an external bath. We show that for a clever choice of this coupling the dissipative model admits a full analytical solution for the steady state current valid at arbitrary frequency, which allows us to fully understand the pumping-frequency dependence of the induced current. We then focus on a different current-controlling scheme exploiting the phenomenon of single-electron tunneling oscillations (SETOs). In this case, opposite to what happens for pumping, an AC effect, an almost periodic current of single electrons, arises through a tunnel junction circuit as a consequence of a DC bias. We study the zero-temperature noise spectrum of a tunnel junction in different resistive environments with the aim to determine the boundaries of the SETOs regime and quantify their quality in terms of periodicity. We then discuss the finite-temperature generalization and the possibility to account for the effects of quantum fluctuations.

Single-electron tunneling (SET) and related phenomena have recently come to be considered as "hot topics". This also became apparent when we organized the 4th International Conference on Superconducting and Quantum Effect Devices and Their Applications, SQUID'91, which was held June 18-21, 1991, in Berlin, Germany. Impressed by the number of contributions dedicated to the new physics of ultrasmall devices, we deemed it appropriate to devote this volume of the Springer Series in Electronics and Photonics to these specialized proceedings. The other contributions presented at SQUID'91, which are more conventional in character but nevertheless contain excitingly innovative results, are published separately as Volume 64 of the series Springer Proceedings in Physics. At first glance it seems strange that a conference abbreviated SQUID'91 should attract so many papers on non-superconducting devices, and in fact the first SQUID'XX conferences dealt exclusively with the physics and technology of Josephson junctions, SQUIDs and other superconducting devices and their ap plications. However, many concepts developed for superconducting devices, like tunneling, flux quantization, and flux-charge conjugation, appeared to be suitable for ultrasmall non-superconducting structures as well, and many researchers in the field of superconducting devices extended their activities accordingly. Thus the extension of the conference programme evolved quite informally. Meanwhile, the meetings established themselves as well-known conference series tradition ally appreciated by the SQUID community for its balanced mixture of physics and technology, review and preview. SQUID'XX became a kind of a trademark.