This work addresses dynamical aspects of quantum criticality in two space dimensions. It probes two energy scales: the amplitude (Higgs) mode, which describes fluctuations of the order parameter amplitude in the broken symmetry phase and the dual vortex superfluid stiffness. The results demonstrate that the amplitude mode can be probed arbitrarily close to criticality in the universal line shape of the scalar susceptibility and the optical conductivity. The hallmark of quantum criticality is the emergence of softening energy scales near the phase transition. In addition, the author employs the charge-vortex duality to show that the capacitance of the Mott insulator near the superfluid to insulator phase transition serves as a probe for the dual vortex superfluid stiffness. The numerical methods employed are described in detail, in particular a worm algorithm for O(N) relativistic models and methods for numerical analytic continuation of quantum Monte Carlo data. The predictions obtained are particularly relevant to recent experiments in cold atomic systems and disordered superconductors.

This book is the first volume of proceedings from the joint conference X International Symposium “Quantum Theory and Symmetries” (QTS-X) and XII International Workshop “Lie Theory and Its Applications in Physics” (LT-XII), held on 19–25 June 2017 in Varna, Bulgaria. The QTS series was founded on the core principle that symmetries underlie all descriptions of quantum systems. It has since evolved into a symposium at the forefront of theoretical and mathematical physics. The LT series covers the whole field of Lie theory in its widest sense, together with its applications in many areas of physics. As an interface between mathematics and physics, the workshop serves as a meeting place for mathematicians and theoretical and mathematical physicists. In dividing the material between the two volumes, the Editor has sought to select papers that are more oriented toward mathematics for the first volume, and those focusing more on physics for the second. However, this division is relative, since many papers are equally suitable for either volume. The topics addressed in this volume represent the latest trends in the fields covered by the joint conferences: representation theory, integrability, entanglement, quantum groups, number theory, conformal geometry, quantum affine superalgebras, noncommutative geometry. Further, they present various mathematical results: on minuscule modules, symmetry breaking operators, Kashiwara crystals, meta-conformal invariance, the superintegrable Zernike system.

This thesis presents and discusses recent optical low-temperature experiments on disordered NbN, granular Al thin-films, and the heavy-fermion compound CeCoIn5, offering a unified picture of quantum-critical superconductivity. It provides a concise introduction to the respective theoretical models employed to interpret the experimental results, and guides readers through in-depth calculations supplemented with supportive figures in order to both retrace the interpretations and span the bridge between experiment and state-of-the art theory.

Ferromagnetism of metallic systems, especially those including transition metals, has been a controversial subject of modern science for a long time. This controversy sterns from the apparent dual character of the d-electrons responsible for magnetism in transition metals, i.e., they are itinerant elec trons described by band theory in their ground state, while at finite tem peratures they show various properties that have long been attributed to a system consisting of local magnetic moments. The most familiar example of these properties is the Curie-Weiss law of magnetic susceptibility obeyed by almost all ferromagnets above their Curie temperatures. At first the problem seemed to be centered around whether the d-elec trons themselves are localized or itinerant. This question was settled in the 1950s and early 1960s by various experimental investigations, in particular by observations of d-electron Fermi surfaces in ferromagnetic transition metals. These observations are generally consistent with the results of band calculations. Theoretical investigations since then have concentrated on explaining this dual character of d-electron systems, taking account of the effects of electron-electron correlations in the itinerant electron model. The problem in physical terms is to study the spin density fluctuati·ons, which are ne glected in the mean-field or one-electron theory, and their influence on the physical properties.

Advances in Chemical Physics covers recent advances at the cutting edge of research relative to chemical physics. The series, Advances in Chemical Physics, provides a forum for critical, authoritative evaluations of advances in every area of the discipline.

' This book presents, in the form of reviews by world''s leading physicists in wide-ranging fields in theoretical physics, the influence and prescience of Skyrme''s daring idea of 1960, originally conceived for nuclear physics, that fermions can arise from bosons via topological solitons, pervasively playing a powerful role in wide-ranging areas of physics, from nuclear/astrophysics, to particle physics, to string theory and to condensed matter physics. The skyrmion description, both from gauge theory and from gauge/gravity duality, offers solutions to some long-standing and extremely difficult problems at high baryonic density, inaccessible by QCD proper. It also offers explanations and makes startling predictions for fascinating new phenomena in condensed matter systems. In both cases, what is at the core is the topology although the phenomena are drastically different, even involving different spacetime dimensions. This second edition has been expanded with addition of new reviews and extensively updated to take into account the latest developments in the field. Contents:Hadrons and Nuclear Matter:Skyrmions and Nuclei (R A Battye, N S Manton and P M Sutcliffe)States of Carbon-12 in the Skyrme Model (P H C Lau and N S Manton)Electromagnetic Form Factors of the Nucleon in Chiral Soliton Models (G Holzwarth)Exotic Baryon Resonances in the Skyrme Model (D Diakonov and V Petrov)Heavy-Quark Skyrmions (N N Scoccola)Pentaquark Candidates P+c(4380) and P+c(4450) within the Soliton Picture of Baryons (N N Scoccola, D O Riska and M Rho)Skyrmion Approach to Finite Density and Temperature (B-Y Park and V Vento)Fractionized Skyrmions in Dense Compact-Star Matter (M Harada, Y-L Ma, H K Lee and M Rho)The Skyrme Model in the BPS Limit (C Adam, C Naya, J Sánchez-Guillén, R Vazquez and A Wereszczyński)Superqualitons: Baryons in Dense QCD (D K Hong)Condensed Matter:Rotational Symmetry Breaking in Baby Skyrme Models (M Karliner and I Hen)Emergent Gauge Fields and Their Nonperturbative Effects in Correlated Electrons (K-S Kim and A Tanaka)Spin and Isospin: Exotic Order in Quantum Hall Ferromanets (S M Girvin)Noncommutative Skyrmions in Quantum Hall Systems (Z F Ezawa and G Tsitsishvili)Meron-Pair Excitations in Bilayer Quantum Hall System (K Moon)Spin and Pseudospin Textures in Quantum Hall Systems (H A Fertig and L Brey)Half-Skyrmion Theory for High-Temperature Superconductivity (T Morinari)Deconfined Quantum Critical Points (T Senthil, A Vishwanath, L Balents, S Sachdev and M P A Fisher)Skyrmions in a Density-Wave State: A Mechanism for Chiral Superconductivity (S Chakravarty and C-H Hsu)String Theory:Skyrmion and String Theory (S Sugimoto)Holographic Baryons (P Yi)The Cheshire Cat Principle from Holography (H B Nielsen and I Zahed)Baryon Physics in a Five-Dimensional Model of Hadrons (A Pomarol and A Wulzer)Holographic Skyrmions (P M Sutcliffe)Holographic Baryons and Instanton Crystal (V Kaplunovsky, D Melnikov and J Sonnenschein) Readership: Research scientists in the fields of condensed matter physics, nuclear and particle physics, and string theory. '

This thesis explores the physics of non-equilibrium quantum dynamics in homogeneous two-dimensional (2D) quantum gases. Ultracold quantum gases driven out of equilibrium have been prominent platforms for studying quantum many-body physics. However, probing non-equilibrium dynamics in conventionally trapped, inhomogeneous atomic quantum gases has been a challenging task because coexisting mass transport and spreading of quantum correlations often complicate experimental analyses. In this work, the author solves this technical hurdle by producing ultracold cesium atoms in a quasi-2D optical box potential. The exquisite optical trap allows one to remove density inhomogeneity in a degenerate quantum gas and control its dimensionality. The author also details the development of a high-resolution, in situ imaging technique to monitor the evolution of collective excitations and quantum transport down to atomic shot-noise, and at the length scale of elementary collective excitations. Meanwhile, tunable Feshbach resonances in ultracold cesium atoms permit precise and dynamical control of interactions with high temporal and even spatial resolutions. By employing these state-of-the-art techniques, the author performed interaction quenches to control the generation and evolution of quasiparticles in quantum gases, presenting the first direct measurement of quantum entanglement between interaction quench generated quasiparticle pairs in an atomic superfluid. Quenching to attractive interactions, this work shows stimulated emission of quasiparticles, leading to amplified density waves and fragmentation, forming 2D matter-wave Townes solitons that were previously considered impossible to form in equilibrium due to their instability. This thesis unveils a set of scale-invariant and universal quench dynamics and provides unprecedented tools to explore quantum entanglement transport in a homogenous quantum gas.

Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivit