Speaker: Dr. Pontus Laurell, University of Missouri

Title: Witnessing quantum correlations and entanglement in materials

Abstract: Entanglement and other nonclassical correlations are ubiquitous in quantum many-body systems. This is well-established in quantum information applications, where they represent resources to be harnessed for quantum operations. However, they also play a prominent role in theories of important condensed matter phenomena, such as novel phases of matter. Yet there has been a distinct lack of viable methods to detect these correlations in the solid state, impeding our ability to identify suitable materials and to unravel their secrets. In this talk I will describe the rapid progress made in recent years towards finding useful measures of these properties, which can both be modeled theoretically and measured experimentally in a model-independent fashion, by making use of information “hidden” in spectroscopic data. By employing entanglement witnesses—quantities that are akin to order parameters for certain classes of entangled states—multipartite entanglement has now been observed in quantum spin systems and strongly correlated electron systems. Such quantum information-informed approaches offer new quantitative insights into many-body states and can provide hints for modeling of enigmatic states in quantum materials.