Molecular interactions control everything from making new materials to generation of energy. However, the complexity of molecular structure and interactions has challenged accurate studies of details and precise control of dynamics. A new scientific frontier is emerging in recent years with the work of cooling molecules to low temperatures, aiming to achieve precise control of molecular interaction processes. This is motivated by new scientific opportunities where fundamental insights of how molecule interact and evolve will allow us to design and control chemistry and quantum materials.
With precise monitoring or control of molecular internal and external degrees of freedom achieved at the quantum level, molecular interactions become understandable from basic quantum mechanics rules. The capability of tracking how multiple molecular species approach each other, interact via their evolving potential energy landscape and form intermediates, and then emerge with final products, along with information of the internal and external energy level distributions will produce first-principle understandings for some of the most fundamental reaction processes. When a quantum gas of molecule is produced, we can confine molecules in specialized spatial configurations and precisely manipulate their interactions via external electromagnetic fields. The long-range dipolar interaction between spatially trapped molecules presents an interconnected spin system where correlated many-body dynamics can be explored.