Quantum chaos on a critical Fermi surface.
We compute parameters characterizing many-body quantum chaos for a critical Fermi surface without quasiparticle excitations. We examine a theory of [Formula: see text] species of fermions at nonzero density coupled to a [Formula: see text] 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 [Formula: see text], the gauge-coupling constant, the Fermi velocity, the Fermi surface curvature, and high-energy details.
Department of Physics, Harvard University, Cambridge, MA 02138; sachdev@g.harvard.edu aavishkarpatel@g.harvard.edu.
Aavishkar A
AA
Patel
Department of Physics, Harvard University, Cambridge, MA 02138; sachdev@g.harvard.edu aavishkarpatel@g.harvard.edu.|Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada.
Subir
0000-0002-2432-7070
S
Sachdev
non-Fermi liquids; quantum chaos; quantum criticality; thermal transport