Entanglement Spectroscopy of Quantum Materials

Entanglement is a key ingredient for the appearance of collective phenomena in quantum materials, yet its experimental exploration remains limited. By leveraging experimentally measurable operators, called entanglement witnesses (EWs), we aim to study the presence of coherent superpositions of quantum states in strongly correlated systems. These EWs extend beyond traditional order parameters, revealing the microscopic structure of entangled states for distinct degrees of freedom. Experimentally witnessing entanglement in nonequilibrium quantum materials could enable the discovery of coherent states without equilibrium analogs and guide the realization of new quantum functionalities. Our research focuses on investigating many-body entanglement in quantum materials in and out of equilibrium with a variety of spectroscopic tools ranging from ultrafast optical spectroscopy to ultrafast x-rays.