This text examines all aspects of constructing and using SQUID magnetic sensors that operate at either liquid helium or liquid nitrogen temperatures (4 or 77 K, respectively). There is comprehensive coverage of a range of established and emerging applications: biomagnetism, geophysics, nondestructive evaluation, detection of unexploded ordnance, and gravity gradiometry. The principles of both dc and rf SQUIDS are discussed extensively, as are the geometries, electronic circuitry and analysis techniques required to maximize performance. A major chapter of SQUID gradiometers in real environments presents original information on how to minimize noise from external sources. The discussions of biomagnetism describe the growing importance of neuromagnetometry with systems employing over 100 SQUID sensors, as well as the emergence of magnetocardiography and foetal heartbeat monitoring. Analysis techniques relevant to both biomagnetism and nondestructive evaluation are presented in depth.

This book provides a current review of recent advances in all aspects of superconducting electronics, both for the tradition (4 K) liquid helium based (LTS) materials and the more recent ceramic (HTS) materials that can operate at higher temperatures in the range of liquid nitrogen (77 K). Special emphasis has been placed on the rapid progress over the past two years in the fabrication of thin-film structures which provide the potential for vastly improved passive elements in microwave circuitry and active components for signal processing and magnetic sensors. The fundamentals of superconducting and single-electron tunneling, as well as a detailed explanation of SQUID fundamentals, are presented. Current and projected applications of superconducting electronic and magnetic-sensing elements are discussed. The book concludes with four chapters devoted to new generations of analog-to-digital converters and digital signal processors. This information should prove valuable to scientists and engineers engaged in R&D on improved electromagnetic sensing and signal processing, the fabrication of thin-film components, and practical applications of rapidly emerging LTS and HTS superconducting technology.

This book should be of value to all those who are considering the use of or have only just begun to use the computer as a learning aid, regardless of the educational level and the discipline being considered. Although the focus is on computer-based instruction in physics and mathematics at the university- and secondary-school levels, the strategies and problems are universally applicable. At the NATO Advanced Study Institute upon which this volume is based, the obstacles encountered by those engaged in such activities were similar in each of the eighteen countries represented. Despite many false starts by those engaged in applying the computer as a learning aid, we believe unequivocally that the computer presents a unique educational tool yet to be exploited adequately. The reasons for slow development may become obvious as one reads this book: the effort required to achieve measurable success is not trivial. Extensive planning and team efforts are often necessary. Unfortunately, many well-intentioned educators discover this too late. We emphasize very early that it is the opportunity to engage students as active participants in the learning process which sets computer-based learning apart from the learning potential of other electronic media.

The book provides an in-depth understanding of the fundamentals of superconducting electronics and the practical considerations for the fabrication of superconducting electronic structures. Additionally, it covers in detail the opportunities afforded by superconductivity for uniquely sensitive electronic devices and illustrates how these devices (in some cases employing high-temperature, ceramic superconductors) can be applied in analog and digital signal processing, laboratory instruments, biomagnetism, geophysics, nondestructive evaluation and radioastronomy. Improvements in cryocooler technology for application to cryoelectronics are also covered. This is the first book in several years to treat the fundamentals and applications of superconducting electronics in a comprehensive manner, and it is the very first book to consider the implications of high-temperature, ceramic superconductors for superconducting electronic devices. Not only does this new class of superconductors create new opportunities, but recently impressive milestones have been reached in superconducting analog and digital signal processing which promise to lead to a new generation of sensing, processing and computational systems. The 15 chapters are authored by acknowledged leaders in the fundamental science and in the applications of this increasingly active field, and many of the authors provide a timely assessment of the potential for devices and applications based upon ceramic-oxide superconductors or hybrid structures incorporating these new superconductors with other materials. The book takes the reader from a basic discussion of applicable (BCS and Ginzburg-Landau) theories and tunneling phenomena, through the structure and characteristics of Josephson devices and circuits, to applications that utilize the world's most sensitive magnetometer, most sensitive microwave detector, and fastest arithmetic logic unit.