1] V.E. Fortov, R.I. Ilkaev, V.A. Arinin, V.V. Burtzev, V.A. Golubev, I.L. Iosilevskiy, V.V. Khrustalev, A.L. Mikhailov, M.A. Mochalov, V.Ya. Ternovoi, and M.V. Zhernokletov, Phase Transition in a Strongly Non-ideal Deuterium Plasma Generated by Quasi-Isentropical Compression at Megabar Pressures, Phys. Rev. Lett. 99, 185001 (2007). [2] T.

Strongly correlated systems of fermions have an interesting phase diagram arising from the Hubbard gap. Excitation across the gap leads to the formation of doubly occupied lattice sites (doublons) which offers interesting electronic and optical properties. Moreover, when the system is driven out of equilibrium interesting collective dynamics may arise that are related to the spatial propagation of doublons. Here, a novel mechanism that was recently proposed by the authors [Balzer et al., Phys. Rev. Lett. 121, 267602 (2018)] is verified by exact diagonalization and nonequilibrium Green functions (NEGF) simulationsfermionic doublon creation by the impact of energetic ions. The formation of a nonequilibrium steady state with homogeneous doublon distribution is reported. The effect should be particularly important for correlated finite systems, such as graphene nanoribbons, and directly observable with fermionic atoms in optical lattices. It is demonstrated that doublon formation and propagation in correlated lattice systems can be accurately simulated with NEGF. In addition to two-time results, single-time results within the generalized Kadanoff-Baym ansatz (GKBA) with Hartree-Fock propagators (HF-GKBA) is presented. Finally systematic improvements of the GKBA that use correlated propagators (correlated GKBA) and a correlated initial state are discussed.

The nonequilibrium Green's functions (NEGF) method has proven to be a powerful tool to describe quantum behavior for a variety of correlated many‐body systems out of equilibrium. The cover image shows results of NEGF calculations of the response of a correlated chain of electrons in a Hubbard lattice to the impact of charged particles. The ions produce a local increase of the double occupation at the impact point, that is spreading through the system. With each successive particle impact the double‐occupation level is significantly increased in time and gives rise to stable, delocalized doublons–bound electron pairs. For more details see article no. http://doi.wiley.com/10.1002/pssb.201800490 by Michael Bonitz et al. within the special section “Non‐Equilibrium Green's Functions”, guest‐edited by Gianluca Stefanucci, Andrea Marini, and Stefano Bellucci (cf. also the Preface, article no. http://doi.wiley.com/10.1002/pssb.201900335).