Understanding light-matter interactions at fast timescales is key to engineering novel functionalities in materials. Achieving this goal involves ultrafast spectroscopy for interrogating quantum dynamics and its control by material design. This talk will focus on ultrafast dynamics in 2D lead-halide perovskite materials. Although known to be good candidates for light-harvesting and emitting applications, a proposed efficient sub-picosecond (ps) inter-layer exciton transport remains debated and poorly understood. Through modelling of quantum dynamics and pump-probe experiments on 2D perovskites, it will be shown that exciton wavefunction leaks across layers, leading to inter-layer exciton transfer. Further, it is found that such exciton delocalization is sensitive to layer ordering, presenting a challenge in understanding how a changing nanostructure modifies sub-ps dynamics. Here, conventional pump- probe methods are limited in spectral and temporal resolution. I will present how multi-dimensional spectroscopy was employed to unravel the nanostructure effect. Following material interaction with a tailored sequence of light pulses, 3-dimensional spectra with detailed information on interlayer electronic coupling are generated. From this, it will be shown that smaller interlayer spacing and subtle changes to structural order can promote delocalization and enhance long-distance exciton transfer. Clarifying these structure-property relationships led to new synthetic approaches for technologies exploiting tunable exciton transfer. I will conclude by presenting a novel approach being developed to improve spectroscopy beyond the bounds of the conventional semi-classical description. Using quantum light, robust optical measurements are possible at low mean photon numbers. I will also show how non-classical photon correlations such as entanglement is characterized using interferometry and showcase the potential of this approach for material characterization. Engineering quantum materials and light thus promise advancements1064 in opto-electronics and platforms for optical spectroscopy