



01260nas a2200133   4500008004100000245006500041210006000106260001400166520085200180100001901032700001901051700001901070856003701089       2020                        eng d00aAn exponential ramp in the quadratic Sachdev-Ye-Kitaev model0 aexponential ramp in the quadratic SachdevYeKitaev model  c6/26/20203 a<p>A long period of linear growth in the spectral form factor provides a universal diagnostic of quantum chaos at intermediate times. By contrast, the behavior of the spectral form factor in disordered integrable many-body models is not well understood. Here we study the two-body Sachdev-Ye-Kitaev model and show that the spectral form factor features an exponential ramp, in sharp contrast to the linear ramp in chaotic models. We find a novel mechanism for this exponential ramp in terms of a high-dimensional manifold of saddle points in the path integral formulation of the spectral form factor. This manifold arises because the theory enjoys a large symmetry group. With finite nonintegrable interaction strength, these delicate symmetries reduce to a relative time translation, causing the exponential ramp to give way to a linear ramp.</p>1 aWiner, Michael1 aJian, Shao-Kai1 aSwingle, Brian  uhttps://arxiv.org/abs/2006.15152