Quantum Phenomena in Solids

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical research on the quantum physics of electrons inside materials. Even a tiny amount of a solid contains an enormous number of electrons, which, when they coordinate their actions, can induce remarkable effects and useful material properties, such as magnetism, switching, and superconductivity. This project seeks to discover new examples of such effects and expand our understanding of existing ones. In particular, the research will study unusual magnets and conductors, make theoretical predictions for experiments to probe their novel quantum capabilities, and determine how to manipulate the electrons within these materials using electromagnetic fields. A core component of the study is to incorporate recently developed abstract theoretical ideas about ways in which electrons can cooperate quantum mechanically, known as entanglement and topological order, into practical proposals for experiments. The results of the research may be the basis of new technologies and quantum devices. All the research will be continuously compared with and referenced to real materials and experiments, with this feedback refining directions for theory to ensure maximum impacts in the laboratory. Training of undergraduate and graduate students and postdoctoral researchers is an integral component of this project. These junior scientists will learn forefront areas of condensed matter and quantum theory, as well as develop general scientific, communication, and computational proficiency, through mentorship and collaboration on the research. These skills prepare them to participate productively in the nation's quantum workforce. TECHNICAL SUMMARY This award supports theoretical research on the quantum physics of quantum magnets and ordered topological metals, to discover the fundamental mechanisms in which electrons act together to produce new states of matter, and to predict what novel properties these states possess. The studies of quantum magnets will determine their dynamics in and out of equilibrium, providing experimentalists with clear signatures to seek in the laboratory, both for highly entangled (e.g. quantum spin liquid) states and for ordered ones. Furthermore, the research will design ways to control materials' properties in situ via oscillating fields. The projects on ordered topological metals address a different way to control materials' properties - their topology - through induced symmetry breaking order. The studies will determine how the topology of electronic states is modified by domains and topological defects of different types of order, such as magnetic domains and domain walls in topological magnets, and in turn, how this topology influences the properties and responses of those domains and defects. All the research will be continuously compared with and references to real materials and experiments, with such feedback refining directions for theory to ensure maximum impacts in the laboratory. Training of undergraduate and graduate students and postdoctoral researchers is an integral component of this project. These junior scientists will learn forefront areas of condensed matter and quantum theory, as well as develop general scientific, communication, and computational proficiency, through mentorship and collaboration on the research. These skills prepare them to participate productively in the nation's quantum workforce. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.