From Bulk to Edge: Realization and Characterization of Fractionalized Quantum Matter

ended

Most phases of matter can be understood using the concept of symmetry breaking. For example, the organization of water molecules in an ice crystal breaks the continuous translational symmetries that are preserved in liquid water. The discovery of the quantum Hall effect triggered a revolution of this concept. It was the first example of topological order, a type of order that cannot be detected with any local measurement and supports exciting new properties. A striking example is the universal transport properties which are so robust that metrologists use them to define the quantum of conductance. Additionally, exotic particles with fractionalized quantum numbers called anyons may emerge as collective excitations of these systems and could provide a route to fault-tolerant quantum computing. Despite the increasingly good theoretical understanding of fractionalized phases, there is a strong need to relate the theories to experimentally relevant models. sharpEDGE will build new bridges between the effective and microscopic descriptions of fractionalized phases of matter. This requires us to solve a cumbersome quantum many-body problem. Numerical methods are essential here: they have accompanied the progress of the field since its early days, and the most recent developments give hope to solve some long-standing issues. We will thus apply a multidisciplinary approach combining the latest advances in topological quantum field theory, quantum information, and material science. Fractionalization may occur in gapped systems such as the fractional quantum Hall effect, lattice topological insulators or frustrated magnets, but also in exotic metallic phases. In this context, we will explore the microscopic relation between the edge and the bulk of gapped topological phases, and develop new characterization tools for gapless phases.