Patel, AavishkarSachdev, Subir2019-10-092017-02-07Patel, Aavishkar A., and Subir Sachdev. 2017. Quantum Chaos on a Critical Fermi Surface. PNAS 114 , no. 8: 1844-1849.0027-84241091-6490http://nrs.harvard.edu/urn-3:HUL.InstRepos:41511329We 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.en-USMultidisciplinaryJournal Article2019-10-0910.1073/pnas.1618185114