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  • Quantum chaos on a critical...
    Patel, Aavishkar A.; Sachdev, Subir

    Proceedings of the National Academy of Sciences - PNAS, 02/2017, Volume: 114, Issue: 8
    Journal Article

    We compute parameters characterizing many-body quantum chaos for a critical Fermi surface without quasiparticle excitations. We examine a theory of N species of fermions at nonzero density coupled to a U(1) gauge field in two spatial dimensions and determine the Lyapunov rate and the butterfly velocity in an extended random-phase approximation. The thermal diffusivity is found to be universally related to these chaos parameters; i.e., the relationship is independent of N, the gauge-coupling constant, the Fermi velocity, the Fermi surface curvature, and high-energy details.