Impact ionization and multiple photon absorption in the two-dimensional photoexcited Hubbard model

We study the nonequilibrium response of a $4\ifmmode\times\else\texttimes\fi{}3$ Hubbard model at $U=8$ under influence short electric field pulse, with main focus on multiple photon excitations and change double occupancy after pulse. The behavior mainly depends driving frequency field. largest occurs during For frequencies below Mott gap, we observe multiphoton large intensities. beyond gap energy, there is region where Auger recombination reduces Impact ionization (multiexciton generation), namely, growing for larger than twice gap. From Loschmidt amplitude, compute eigenstate spectrum quantum state observing distinct excitation peaks, in line expectations from quasiparticle picture. introduce technique which analyze time evolution each peak individually. long-term almost only absorbed explore connection this property to thermalization hypothesis.