This book contains a coherent and self-contained account of macroscopic quantum phenomena, focusing on the central role played by macroscopic quantum tunneling. Beginning with an explanation of the nature and significance of the Schrödinger's cat concept, Shin Takagi introduces macroscopic quantum tunneling. He deals with typical examples in detail, elucidating how quantum mechanical coherence may be lost (so-called "decoherence") or how it may be maintained despite the effects of environment and measurement processes. Assuming only a knowledge of elementary quantum mechanics, this book emphasizes conceptual aspects rather than technical details.

Macroscopic quantum phenomena are particularly important when considering the problem of Schroedinger's cat. This book contains a coherent and self-contained account of such phenomena, focusing on the central role played by macroscopic quantum tunneling. Beginning with an explanation of the nature and significance of the cat problem, Shin Takagi introduces the concept of macroscopic quantum tunneling. He deals with typical examples in detail, elucidating how quantum mechanical coherence may be lost (so-called 'decoherence') or how it may be maintained despite the effects of environment and measurement processes. Recent experimental and theoretical advances are discussed, and the remaining problems described. The final chapter describes an experiment to decide between quantum mechanics and macrorealism in the light of Einstein's moon. Assuming only a knowledge of elementary quantum mechanics, this book emphasises conceptual aspects rather than technical details. It provides a firm introduction to the subject for graduate students and researchers.

The contributors of this volume are working at the forefront of various realizations of quantum computers. They survey the recent developments in each realization, in the context of the DiVincenzo criteria, including nuclear magnetic resonance, Josephson junctions, quantum dots, and trapped ions. There are also some theoretical contributions which have relevance in the physical realizations of a quantum computer. This book fills the gap between elementary introductions to the subject and highly specialized research papers to allow beginning graduate students to understand the cutting-edge of research in the shortest possible time.