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TT: Fachverband Tiefe Temperaturen
TT 25: Nonequilibrium Quantum Systems I (joint session TT/DY)
TT 25.5: Talk
Tuesday, March 19, 2024, 10:30–10:45, H 3005
Non-equilibrium Eliashberg theory for photon-mediated superconductivity — •Michele Pini1, Christian H. Johansen1,2, and Francesco Piazza3,1 — 1Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany — 2Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziadzka 5, 87-100 Toruń, Poland — 3Institute of Physics, Universität Augsburg, 86159 Augsburg, Germany
In the recent years, new mechanisms have been proposed to induce photon-mediated superconductivity in a non-thermal steady-state. Within these settings, the photon-electron interaction which generates the pairing can assume a form analogous to an electron-phonon interaction. This suggests a description of the superconducting phase transition within Eliashberg theory, similarly to phonon-mediated superconductivity. However, as soon as photons and electrons are pulled away from mutual equilibrium, a standard Matsubara formulation of Eliashberg theory becomes impossible. To tackle this issue, we derive a more general non-equilibrium version of Eliashberg theory. We then apply this theory to describe the superconducting phase transition in a generic non-thermal steady-state setting. We present a numerical solution of the non-equilibrium Eliashberg equations and show that bringing the system out of equilibrium can have dramatic effects on the superconducting phase transition.
Note: The authors M. Pini and C. H. Johansen contributed to this work equally.
Keywords: Superconductivity; Photon-mediated pairing; Eliashberg theory; Non-equilibrium Green's function formalism; Non-thermal steady-state