Nonequilibrium dynamics in strongly correlated systems: spin-charge coupling in a photodoped Mott insulator and possible induced superconductivity

Firstly, using a nonequilibrium implementation of the extended dynamical mean field theory (EDMFT) we simulate the relaxation of a photo-excited doped Mott insulator [3]. We consider the t-J model and focus on the interplay between the charge- and spin-dynamics in different excitation and doping regimes. In particular, we observe a correlated oscillatory evolution of the kinetic energy and spin-spin correlation function after a photoexcitation, which is a direct consequence of strong spin-charge coupling. Moreover, we propose a pump-probe setup, which allows to directly observe these oscillations in the optical conductivity originating from string states (see Fig. (a)).Secondly, within the framework of the time-dependent Lanczos algorithm we demonstrate [4] that the possible light-induced superconducting coherence can emerge as a result of the modulated effective correlations (see Fig. (b)). Here, we investigate two different nonequilibrium scenarios: (i) an interaction quench and (ii) action of a light pulse. In both cases we could identify a possible transient Meissner effect, which is a fingerprint of the induced superconductivity. In addition, we find that the stability of the possible induced superconducting state depends crucially on the nature of the excitation quench: namely, a pure interaction quench induces a long-lived superconducting state, whereas a phase quench leads to a short-lived transient superconductor.[1] S. Dal Conte et al. Science, 335, 1600 (2012) [2] S. Kaiser et al. PRB, 89, 184516 (2014); D. Fausti et al. Science 331, 189 (2011); M. Mitrano et al. Nature, 530, 461 (2016)[3] N. Bittner et al. PRB, 97, 235125 (2018) [4] N. Bittner et al. arxiv:1706.09366