Explicit derivation of duality between a free Dirac cone and quantum electrodynamics in (2+1) dimensions

We explicitly derive the duality between a free electronic Dirac cone and quantum electrodynamics in (2+1) dimensions (QED_3) with N=1 fermion flavors. The duality proceeds via an exact, non-local mapping from electrons to dual fermions with long-range interactions encoded by an emergent gauge field. This mapping allows us to construct parent Hamiltonians for exotic topological-insulator surface phases, derive the particle-hole-symmetric field theory of a half-filled Landau level, and nontrivially constrain QED_3 scaling dimensions. We similarly establish duality between bosonic topological insulator surfaces and N=2 QED_3