Photoexcitations in the Hubbard model -- generalized Loschmidt amplitude analysis of impact ionization in small clusters

Abstract

We study photoexcitations in small Hubbard clusters of up to 12 sites, some of which show an increase of the double occupation after the electric field pulse through impact ionization. Here, the time-dependent electromagnetic field is introduced through a Peierls substitution and the time evolution is calculated by exact diagonalization with commutator-free Magnus integrators. As a tool to better analyze the out-of-equilibrium dynamics, we generalize the Loschmidt amplitude. This way, we are able to resolve which many-body energy eigenstates are responsible for impact ionization and which show pronounced changes in the double occupation and spin energy. This analysis reveals that the loss of spin energy is of little importance for impact ionization. We further demonstrate that, for one-dimensional chains, the optical conductivity has a characteristic peak structure originating solely from vertex corrections.

21 pages, 16 figures

References in corpus (9)

• Dynamics of Loschmidt echoes and fidelity decay
• Oxide Heterostructures for Efficient Solar Cells
• Role of impact ionization in the thermalization of photo-excited Mott insulators
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• A new pathway to impact ionization in a photo-excited one-dimensional ionic Hubbard model
• Photodriven Mott insulating heterostructures: A steady-state study of impact ionization processes