Lee worked with collaborators Evgeny Epelbaum, Hermann Krebs, and Ulf-G. Meißner, to perform the first ab initio calculations of the Hoyle state of carbon-12. He also worked with collaborators Serdar Elhatisari, Gautam Rupak, Epelbaum, Krebs, Timo Lähde, Thomas Luu, and Meißner, on the first ab initio calculation of alpha-alpha scattering. His research group also works on new technologies and computational paradigms such as eigenvector continuation, machine learning tools to find hidden correlations, and quantum computing algorithms for the nuclear many-body problem. Lee and collaborators are perhaps most well known for developing lattice effective field theory. Effective field theory (EFT) is an organizing principle for the interactions of a complex system at low energies. When applied to low-energy protons and neutrons in a formulation called chiral EFT, it functions as an expansion in powers of the nucleon momenta and the pion mass. Lattice EFT combines this theoretical framework with lattice methods and Monte Carlo algorithms that are applicable to few-body systems, heavier nuclei, and infinite matter. The Lee research group is part of the Nuclear Lattice EFT Collaboration, which has pioneered many of the theoretical ideas and methods now being used in lattice EFT calculations.