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

We study the real-time dynamics of a pair
hole/doubly-occupied-site, 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 inter-site 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.
Due to 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.