Positivity of the Spectral Densities of Retarded Floquet Green Functions

ORAL

Abstract

Periodically driven nonequilibrium many-body systems are interesting because they have quasi-energy spectra, which can be tailored by controlling the external driving fields. We derive the general spectral representation of retarded Green functions in the Floquet regime, thereby generalizing the well-known Lehmann representation from equilibrium many-body physics. The derived spectral Floquet representation allows us to prove the non-negativity of spectral densities and to determine exact spectral sum rules, which can be employed to benchmark the accuracy of approximations to the exact Floquet many-body Green functions.

This work appears in Phys. Rev. Lett. 122, 130604 (2019).

*This abstract was supported by the Deutsche Forschungsgemeinschaft (Grant No. UH 90-13/1) (GSU) and by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-FG02-08ER46542 (JKF); JKF also acknowledges financial support from the McDevitt Bequest at Georgetown. MHK acknowledges the financial support by the Studienstiftung des Deutschen Volke.

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Presenters

  • James Freericks

    • Physics, Georgetown University
    • Georgetown University
    • Department of Physics, Georgetown University

Authors

  • James Freericks

    • Physics, Georgetown University
    • Georgetown University
    • Department of Physics, Georgetown University

  • Mona Kalthoff

    • Physics, University of Hamburg
    • Max Planck Institute for the Structure and Dynamics of Matter

  • Goetz S Uhrig

    • Lehrstuhl für Theoretische Physik I, Technische Universität Dortmund
    • Physics, University of Dortmund