Uses MBE thin-film growth combined with equilibrium and non-equilibrium ARPES to sense electronic structure at material interfaces. Directions: (1) non-equilibrium photoemission (tr-ARPES) to map ultrafast electron dynamics in topological and superconducting materials; (2) MBE engineering of interfacial superconductivity and topological orders at oxide and chalcogenide interfaces; (3) light-induced phase transitions probed by ultrafast ARPES as a sensing modality for correlated electron dynamics.