Quantum materials host some of the most interesting states of matter known to physics, including unconventional superconductors, magnets, and topologically ordered phases. They offer a rich, highly tunable environment for both fundamental physics and potential technological applications. Yet, their inherent complexity makes understanding them challenging. A new generation of experimental probes is now opening new windows into these systems. Nonlinear and terahertz spectroscopies reveal collective excitations invisible to conventional measurements. Qubit-based sensors exploit quantum coherence to probe matter at microwave and THz frequencies. Scanning probes–from superconducting quantum interference devices to nitrogen-vacancy centers in diamond and the quantum twisting microscope–provide real-space, nanoscale access to correlated and topological phases. This program will pursue outstanding open questions: What are the defining signatures of electronic collective modes in novel correlated materials? Can fractionalization in quantum spin liquids be unambiguously detected? What new electronic and magnetic orders–including fractional anomalous Chern insulators and altermagnets–remain to be discovered and characterized? A central goal is to forge a tight theory–experiment loop: using new probes to answer theoretical questions, while developing the theoretical framework needed to connect experimental signals to microscopic physics.