Quantum Monte Carlo Simulations in Momentum Space

Summary: In this study, exact analytic expressions for the energies and wave functions of charged and neutral excitations above the ground state in twisted bilayer graphene are determined, considering various forms of Coulomb interaction and tunneling. It was found that the Cooper pair binding energy is zero in all projected Coulomb models for actual TBG bands, indicating that superconductivity may require other factors such as phonons or nonzero kinetic energy. The study also suggests that if superconductivity is driven by kinetic terms, the highest critical temperature may not necessarily occur at the maximum density of states.