Quantum Tunneling In Complex Systems

In the last two decades remarkable progress has been made in understanding and describing tunneling processes in complex systems in terms of classical trajectories. This book introduces recent concepts and achievements with particular emphasis on a dynamical formulation and relations to specific systems in mesoscopic, molecular, and atomic physics. Advanced instanton techniques, e.g. for decay rates and tunnel splittings, are discussed in the first part. The second part covers current developments for wave-packet tunneling in real-time, and the third part describes thermodynamics and dynamical approaches for barrier transmission in statistical, particularly dissipative systems.

In the last two decades remarkable progress has been made in understanding and describing tunneling processes in complex systems in terms of classical trajectories. This book introduces recent concepts and achievements. There is particular emphasis on a dynamical formulation and relations to specific systems in mesoscopic, molecular, atomic and nuclear physics.

Quantum tunneling is an intriguing phenomenon arising in a multitude of physical contexts. New experiments in systems as wide ranging as superdeformed nuclei, Bose-Einstein condensed gases, and nanomagnetic systems are spurring theoretical studies into the fundamental nature of tunneling. In this volume, the articles include: (i) tunneling out of a metastable state, (ii) coherence between two wells in tunneling contact, (iii) the consequences of the nature of the underlying dynamics (i.e. regular motion, chaos or some mixture) in low-dimensional systems and its connection to newly identified tunneling phenomena such as chaos-assisted tunneling, (iv) nanomagnetic systems with focus on comparing environmental descriptions of nuclear spins and oscillators, (v) solitons in Bose condensates, (vi) tunneling out of the nuclear superdeformed well and its use as a probe of pairing and chaos in excited nuclear states, and (vii) problems linked to the Bose condensed phase of atomic alkali gases. These subjects and others are gathered in six pedagogical courses given during the spring of 1997 at the National Institute of Nuclear Physics program “Tunneling in complex systems”. The purpose of the courses was to give graduate students and postdoctoral researchers exposure to a sampling of such recent theoretical advances and experimental contexts of tunneling as well as a bridge for the communication gaps between researchers in the various fields concerned with tunneling. Contents:Some General Aspects of Quantum Tunneling and Coherence: Application to the BEC Atomic Gases (A J Leggett)Tunneling in Two Dimensions (S C Creagh)Quantum Environments: Spin Baths, Oscillator Baths, and Applications to Quantum Magnetism (P C E Stamp)Coherent Magnetic Moment Reversal in Small Particles with Nuclear Spins (A Garg)Tunneling from Super- to Normal-Deformed Minima in Nuclei (T L Khoo)Solitons in the Bose Condensate (W P Reinhardt) Readership: Physicists in any domain working or interested in the theory of tunneling, BEC, superdeformation and nanomagnetic systems. Keywords:Tunneling;Coherence;Chaos;Quantum Environment;Spin Baths; Quantum Magnetism;Low-Dimensional Systems;Bose Condensates;Super-Deformed Nuclei;Non-Linear Schroedinger Equation;WKB Method;Instantons;Complex Systems;Solitons

The influential political philosopher Leo Strauss has been credited by conservatives with the recovery of the great tradition of political philosophy stretching back to Plato. Among Strauss's most enduring legacies is a strongly negative assessment of Nietzsche as the modern philosopher most at odds with that tradition and most responsible for the sins of twentieth-century culture—relativism, godlessness, nihilism, and the breakdown of family values. In fact, this apparent denunciation has become so closely associated with Strauss that it is often seen as the very core of his thought. In Leo Strauss and Nietzsche, the eminent Nietzsche scholar Laurence Lampert offers a controversial new assessment of the Strauss-Nietzsche connection. Lampert undertakes a searching examination of the key Straussian essay, "Note on the Plan of Nietzsche's Beyond Good and Evil." He shows that this essay, written toward the end of Strauss's life and placed at the center of his final work, reveals an affinity for and debt to Nietzsche greater than Strauss's followers allow. Lampert argues that the essay comprises the most important interpretation of Nietzsche ever published, one that clarifies Nietzsche's conception of nature and of human spiritual history and demonstrates the logical relationship between the essential themes in Nietzsche's thought—the will to power and the eternal return.

Topics of complex system physics and their interdisciplinary applications to different problems in seismology, biology, economy, sociology, energy and nanotechnology are covered in this new work from renowned experts in their fields. In particular, contributed papers contain original results on network science, earthquake dynamics, econophysics, sociophysics, nanoscience and biological physics. Most of the papers use interdisciplinary approaches based on statistical physics, quantum physics and other topics of complex system physics. Papers on econophysics and sociophysics are focussed on societal aspects of physics such as, opinion dynamics, public debates and financial and economic stability. This work will be of interest to statistical physicists, economists, biologists, seismologists and all scientists working in interdisciplinary topics of complexity.

A prominent aspect of quantum theory, tunneling arises in a variety of contexts across several fields of study, including nuclear, atomic, molecular, and optical physics and has led to technologically relevant applications in mesoscopic science. Exploring mechanisms and consequences, Dynamical Tunneling: Theory and Experiment presents the work of i

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.

This book provides a comprehensive introduction to the theoretical foundations of quantum tunneling, stressing the basic physics underlying the applications. The topics addressed include exponential and nonexponential decay processes and the application of scattering theory to tunneling problems. In addition to the Schrödinger equation approach, the path integral, Heisenberg's equations and the phase space method are all used to study the motion of a particle under the barrier. Extensions to the multidimensional cases and tunneling of particles with internal degrees of freedom are also considered. Furthermore, recent advances concerning time delay and tunneling times and some of the problems associated with their measurement are also discussed. Finally, some examples of tunneling in atomic, molecular, nuclear and condensed matter physics are presented.