A coherent and self-contained account of macroscopic quantum phenomena for graduate students and researchers.

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.

The first NATO Advanced Workshop on Quantum Tunneling of Magnetization (QTM) was organized and co-directed by Bernard Barbara, Leon Gunther, Nicolas Garcia, and Anthony Leggett and was held from June, 27 through July 1, 1994 in Grenoble and Chichilianne, France. These Proceedings include twenty-nine articles that represent the contributions of the participants in the Workshop. Quantum Tunneling of Magnetization is not only interesting for purely academic reasons. It was pointed out in the review article by L. Gunther in the December, 1990 issue of Physics World, that QTM may be destined to play a significant role within the next two decades in limiting the density of information storage in magnetic systems. Recent advances have indicated that this limitation may well be reached even earlier than first predicted. Furthermore, the number of people who have entered the field of study of QTM during these past few years has increased many fi)ld. The time was therefore opportune to hold a Workshop to bring together for the first time the leading researchers of QTM, both theoretical and experimental, so as to discuss the current status of the field. The most controversial issue at the time of the Workshop was how to establish r.eliable criteria for determining whether experimental results do indeed reveal manifestations of QTM. We believe that much progress was made at the Workshop on this issue.

This is the first book presenting a coherent theoretical and experimental treatment of the rapidly developing field of macroscopic quantum tunneling of the magnetic moment. The theory is based on the concept of the magnetic instanton and its renormalization by the dissipative environment. The book includes discussions of the tunneling of magnetic moment in small ferromagnetic grains, tunneling of the Ne'el vector in antiferromagnetic grains, quantum nucleation of magnetic domains, and quantum depinning of domain walls. The experimental part collects the majority of recent data that are, or may be, relevant to spin tunneling. Among the topics described are low temperature magnetic relaxation and its interpretation in various systems, experiments on single particles and mesoscopic wires, and resonant spin tunneling in molecular magnets. This study of an important new field in condensed matter physics by two leading contributors to the subject will be of interest to theorists and experimentalists alike.

Develops the basic material necessary to understand the quantum dynamics of macroscopic variables. Ideal for graduate students and researchers.

Explores the role of quantum mechanics in biology for advanced undergraduate and graduate students in physics, biology and chemistry.