Excitons in the One-Dimensional Hubbard Model: A Real-Time Study...

We study the real-time dynamics of a hole and doubly occupied site pair, namely, a holon and a
doublon, in a 1D Hubbard insulator with on-site and nearest-neighbor Coulomb repulsion. Our analysis
shows that the pair is long-lived and the expected decay mechanism to underlying spin excitations is
actually inefficient. For a nonzero intersite Coulomb repulsion, we observe that part of the wave function
remains in a bound state. Our study also provides insight on the holon-doublon propagation in real space.
Because of the one-dimensional nature of the problem, these particles move in opposite directions even in
the absence of an applied electric field. The potential relevance of our results to solar cell applications is
discussed.