This thesis presents the first ever measurement of the noise emitted by magnetic monopoles and the development of an exquisitely sensitive magnetic-field-noise spectrometer based on a superconducting quantum interference device (SQUID) that enabled it. Magnetic monopoles are highly elusive elementary particles exhibiting quantized magnetic charge. The prospects for studying them brightened recently with the theoretical discovery that the thermally excited states in certain classes of magnetic insulators exhibit all the characteristics of magnetic monopoles. Furthermore, in 2018, it was predicted that the random motion of magnetic monopoles inside would generate a very specific kind of magnetization noise. In this thesis, the author describes a new experimental technique, so-called spin noise spectroscopy, and the subsequent discovery of virtually all of the predicted features of the magnetic noise expected from a dense fluid of magnetic monopoles in crystals of Dy2Ti2O7. Remarkably, because this magnetic monopole noise occurs in the frequency range below 20kHz, when amplified by the SQUID it is actually audible to humans.

In 1269 Petrus Peregrinus observed lines of force around a lodestone and noted that they were concentrated at two points which he designated as the north and south poles of the magnet. Subsequent observation has confirmed that all magnetic objects have paired regions of' opposite polarity, that is, all magnets are dipoles. It is easy to conceive of an isolated pole, which J.J. Thomson did in 1904 when he set his famous problem of the motion of an electron in the field of a magnetic charge. In 1931 P.A.M. Dirac solved this problem quantum mechanically and showed that the existence of a single magnet pole anywhere in the universe could explain the mystery of charge quantization. By late 1981, theoretical interest in monopoles had reached the point where a meeting was organized at the International Centre for Theoretical Physics in Trieste. Many mathematical properties of monopoles were discussed at length but there was only a solitary account describing experiments. This imbalance did not so much reflect the meeting's venue as it indicated the relative theoretical and experimental effort at that point.

As heard on BBC Radio 4 Start The Week 'Felix Flicker brilliantly reveals the secrets behind the modern-day magic we call physics' Marcus du Sautoy Imagine you had a crystal that lit upon your command: magic must be at work, and you must surely be a wizard. But what if you discovered that you routinely cast such spells? Are the spells no longer magic ... or are you a wizard? The modern term for wizardry is condensed matter physics. It is the study of the world around us - the states of matter and how they emerge from the quantum realm. Thanks to its practical magic we can make lasers which cut through solid metal, trains which hover in mid-air, and crystals which light our homes. It is one of the best-kept secrets in science; a third of all physicists work on it, yet its story has never been told. Join Felix Flicker as he introduces the magic of condensed matter physics. It will be a journey that reveals the subtle spells that conjure crystals from chaos and create new particles that have never before existed. The Magick of Matter will revolutionise what you know about physics and reality; you'll never see the world in the same way again.

Principles and applications of SQUIDs serves as a textbook and a multi-author collection of critical reviews. Providing both basic aspects and recent progress in SQUIDs technology, it offers a realistic and stimulating picture of the state of the art. It can also contribute to a further development of the field for commercial applications.

Ten years have passed since It Hooft and Polyakov demonstrat ed that superheavy magnetic monopoles were a natural consequence of any Grand Unified Theory (GUT) in which the unifying group contains a U(l) factor as a subgroup. An analysis of these GUTs in an expanding, cooling universe yields a phase transition at an energy ~l015 GeV and at a cosmic time ~lO-35 seconds after the big bang. The general consequences of GUTs and this phase transition are the prediction of proton decay, the production of superheavy magnetic monopoles, and an understanding of the observed excess of matter over anti-matter in the universe. Attempts to provide experimental verification of GUTs has led to valiant experimental efforts in recent years to observe nucleon decay in massive underground detectors. Experiments to search for superheavy monopoles may eventually require similar efforts. Since the unification scale is unreachable in the laboratory, monopole detectors must search for relics of the big bang. Much theoretical groundwork has been accomplished in recent years with the development of GUTs. In Part I of this book, Erick Weinberg gives a theoretical overview of the role of magnetic monopoles in the various unification schemes. Monopoles in the context of the newly revived Kaluza-Klein theories are presented by several authors and are summarized by Qaisar Shafi. Mike Turner begins Part II with a discussion of monopoles in standard big bang cosmology. Paul Steinhardt follows with his perspectives on the inflationary universe; C.

This book contains an interdisciplinary selection of timely articles which cover a wide range of superconducting technologies ranging from high tech medicine (10-12 Gauss) to multipurpose sensors, microwaves, radio engineering, magnet technology for accelerators, magnetic energy storage, and power transmission on the 109 watt scale. It is aimed primarily at the non-specialist and will be suitable as an introductory course book for those in the relevant fields and related industries. As shown in the title several examples of high-Tc applications are included. While low-Tc is still the leading technology, for instance, in cables and SQUIDS, case studies in these areas are presented.

These lecture notes discusses the developments both in the theoretical understanding of the physics and mathematics of magnetic monopoles as well as the ways in which they can be detected experimentally.The subject has now become highly interdisciplinary and recent monopole meetings have attracted participants from low temperature physics at one extreme to cosmology at the other.