This project utilizes quantum spin defects hosted in diamond and atomically thin hexagonal boron nitride (hBN) to study how quantum systems behave when pushed away from equilibrium and how our everyday classical behavior emerges from underlying rules. These spin defects can be prepared and read out with optical light at room temperature, making them an ideal quantum platform without the need for complex cryogenic or vacuum hardware. Insights from these studies enable a better understanding of and prediction of the behavior of a complex quantum system and guide the design of improved quantum based simulators and sensors with important applications in science, technology, and national needs. The project also involves extensive education and outreach activities: developing an advanced undergraduate quantum laboratory, launching an annual “quantum open house” for regional colleges, and engaging secondary-school students and teachers across the greater St. Louis area through existing partnerships (e.g., the NSF NRT program in quantum sensing and the St. Louis Area Physics Teachers Association). Technically, the project will develop and employ two complementary room-temperature solid-state spin platforms: 3D ensembles of nitrogen vacancy (NV) centers in diamond and 2D spin defects in hBN. Both platforms offer unique advantages: a large number of quantum spins, optical initialization and readout at room temperature, long quantum coherence and lifetimes, strong and tunable long-r