Quantum Probes of Matter

What do modern materials measurement and characterization techniques measure? How can experimental signals be connected to microscopic properties of matter? Quantum Probes of Matter develops a unified theoretical framework connecting experimental signals to microscopic structures, excitations, interactions, and dynamics. It balances foundational quantum theoretical frameworks and classic experiments with recent literature and even emerging AI approaches. Quantum Probes of Matter introduces the theoretical tools needed to describe measurement in many-body systems. These include second quantization, Green's functions as a building block, correlation functions as measurables, fluctuation-dissipation theorem, and linear-response theory as two pillars for measurements near equilibrium. These ideas are developed with a direct connection to experimentally measurable quantities rather than as abstract formalism. They are then applied to major characterization methods, including X-ray and neutron diffraction, optical response and X-ray absorption spectroscopy, scanning tunnelling spectroscopy, resonant scattering, angle-resolved photoemission spectroscopy, inelastic neutron scattering, and X-ray photon correlation spectroscopy. The final chapter explores the growing role of artificial intelligence (AI) in materials characterization, inverse problems, and materials discovery.Mingda Li aims to bridge the language of quantum theory and advanced experiment. Experimentalists are shown how measured features can be related to microscopic interactions and many-body correlation functions, while theorists are given a practical understanding of what experiments measure and how probes can be designed. Classical examples are combined with recent studies of quantum materials, with step-by-step derivations that retain conventions and important prefactors wherever useful.