Strichartz estimates for the Schrödinger equation on compact manifolds with nonpositive sectional curvature

Abstract: We obtain improved Strichartz estimates for solutions of the Schr\"odinger equation on compact manifolds with nonpositive sectional curvatures which are related to the classical universal results of Burq, G\'erard and Tzvetkov [11]. More explicitly, we are able refine the arguments in the recent work of Blair and the authors [3] to obtain no-loss $L^p_tL^{q}_{x}$-estimates on intervals of length $\log \lambda\cdot \lambda^{-1} $ for all {\em admissible} pairs $(p,q)$ when the initial data have frequencies comparable to $\lambda$, which, given the role of the Ehrenfest time, is the natural analog in this setting of the universal results in [11]. We achieve this log-gain over the universal estimates by applying the Keel-Tao theorem along with improved global kernel estimates for microlocalized operators which exploit the geometric assumptions.