In the last decade it has become increasingly evident that strong correla- tions between electrons are an essential and unifying factor in such diverse phenomena within solid state physics as high-temperature superconductivity, colossal magnetoresistance, the quantum Hall effect, heavy-fermion metals and Coulomb blockade in single-electron transistors. A new paradigmofnon- FermiLiquidbehaviourisalsoemergingand, inanumberofsystems, replacing the Fermi liquid, which has been the cornerstone ofthe physics of metals and superconductors for the pastdecades. In spite of major achievements, the theoretical studies and understanding of strongly-correlated electrons seems to be still in its infancy. Anomalous electron properties have been studied in some generic models of correlated electrons, such as the Hubbard and t-J models, the Anderson and Kondo impurity models, and their lattice equivalents. New insights into the behaviour of these, and related models is emerging from the introduction of powerful numerical methods to study such many-body models, including approximate techniquesofmany-body theory and exactresults inlow-andhigh-dimensional systems. Theseall showconvincingevidenceforbreakdownoftheFermiliquid concept. The Bled workshop focused on several major open questions in the theory of anomalous metals with correlated electrons. These theoretical advances were complemented by the latest experimental results in related materials, presented by leading experimentalists in the field. The main emphasis was on the following topics: - physics ofcuprates and high-temperature superconductors, - charge- and spin-ordering and fluctuations, - manganites and colossal magnetoresistance, - low-dimensional systems and transport, - Mott-Hubbard transition and infinite dimensional systems, - quantum Hall effect.

Mesoscopic physics has made great strides in the last few years. It is an area of research that is attractive to many graduate students of theoretical condensed matter physics. The techniques that are needed to understand it go beyond the conventional perturbative approaches that still form the bulk of the graduate lectures that are given to students. Even when the non-perturbative techniques are presented, they often are presented within an abstract context. It is important to have lectures given by experts in the field, which present both theory and experiment in an illuminating and inspiring way, so that the impact of new methodology on novel physics is clear. It is an apt time to have such a volume since the field has reached a level of maturity. The pedagogical nature of the articles and the variety of topics makes it an important resource for newcomers to the field. The topics range from the newly emerging area of quantum computers and quantum information using Josephson junctions to the formal mathematical methods of conformal field theory which are applied to the understanding of Luttinger liquids. Electrons which interact strongly can give rise to non-trivial ground states such as superconductivity, quantum Hall states and magnetism. Both their theory and application are discussed in a pedagogical way for quantum information in mesoscopic superconducting devices, skyrmions and magnetism in two dimensional electron gases, transport in quantum wires, metal-insulator transitions and spin electronics.

This book is unique in covering phenomena in photon- matter interactions in a unified way over a range of many orders in energy. The quantum field theoretic approach to the fully relativistic theory of quantum electrodynamics (QED) is presented together with the non- relativistic theory in both confined and unconfined geometries. The predictions of QED have been verified to a greater accuracy than any other physical theory. Moreover QED is a paradigm for other gauge theories and is presented in such a way that the generalisation to other gauge theories is natural. Gauge and Poincare symmetry properties and the non-existence of a photon wave function are thoroughly discussed. Starting from the Dirac equation the non-relativistic interaction of the electron with the electromagnetic field is derived as an effective Hamiltonian of multipole expansions. Much of quantum optics is based on the lowest order dipole approximation. From this point on the treatment of fully relativistic QED and quantum optics is done in parallel. Applications of perturbation theory such as Compton and Moller scattering and the theory photdetection are given. After the impressive successes of QED, the limitation of the theory and the necessity of electroweak theory and quantumchromodynamics are discussed. The remaining chapters are devoted to quantum optics inside cavaties. Various approaches to open systems such as master equations are discussed within the context of active systems (e.g. the laser) and passive systems. Semi- classical approximarions are shown to imply a rich non- linear dynamics including chaos for certain parameter regimes. The effect of fluctuations on such non-linear dynamics is also studied. The final chapter is devoted to highly non- classical states of the light field such as photon number, squeezed and two photon entangled states. The latter are studied for the important system of parametric down conversion and the localisation properties of photons are characterised in terms of asympotic tails in photodetection probabilities as a function of time delay. The range of the book has wider benefits. Workers in quantum optics will gain a deeper understanding of the foundations of their subject and field theorists will see concrete examples of open systems, which are beginning to impinge on fundamental theories.

Mesoscopic physics has made great strides in the last few years. It is an area of research that is attractive to many graduate students of theoretical condensed matter physics. The techniques that are needed to understand it go beyond the conventional perturbative approaches that still form the bulk of the graduate lectures that are given to students. Even when the non-perturbative techniques are presented, they often are presented within an abstract context. It is important to have lectures given by experts in the field, which present both theory and experiment in an illuminating and inspiring way, so that the impact of new methodology on novel physics is clear. It is an apt time to have such a volume since the field has reached a level of maturity. The pedagogical nature of the articles and the variety of topics makes it an important resource for newcomers to the field. The topics range from the newly emerging area of quantum computers and quantum information using Josephson junctions to the formal mathematical methods of conformal field theory which are applied to the understanding of Luttinger liquids.

Electrons which interact strongly can give rise to non-trivial ground states such as superconductivity, quantum Hall states and magnetism. Both their theory and application are discussed in a pedagogical way for quantum information in mesoscopic superconducting devices, skyrmions and magnetism in two dimensional electron gases, transport in quantum wires, metal-insulator transitions and spin electronics.

In the last decade it has become increasingly evident that strong correla- tions between electrons are an essential and unifying factor in such diverse phenomena within solid state physics as high-temperature superconductivity, colossal magnetoresistance, the quantum Hall effect, heavy-fermion metals and Coulomb blockade in single-electron transistors. A new paradigmofnon- FermiLiquidbehaviourisalsoemergingand, inanumberofsystems, replacing the Fermi liquid, which has been the cornerstone ofthe physics of metals and superconductors for the pastdecades. In spite of major achievements, the theoretical studies and understanding of strongly-correlated electrons seems to be still in its infancy. Anomalous electron properties have been studied in some generic models of correlated electrons, such as the Hubbard and t-J models, the Anderson and Kondo impurity models, and their lattice equivalents. New insights into the behaviour of these, and related models is emerging from the introduction of powerful numerical methods to study such many-body models, including approximate techniquesofmany-body theory and exactresults inlow-andhigh-dimensional systems. Theseall showconvincingevidenceforbreakdownoftheFermiliquid concept. The Bled workshop focused on several major open questions in the theory of anomalous metals with correlated electrons. These theoretical advances were complemented by the latest experimental results in related materials, presented by leading experimentalists in the field. The main emphasis was on the following topics: - physics ofcuprates and high-temperature superconductors, - charge- and spin-ordering and fluctuations, - manganites and colossal magnetoresistance, - low-dimensional systems and transport, - Mott-Hubbard transition and infinite dimensional systems, - quantum Hall effect.