On the mixing and Bernoulli properties for geodesic flows on rank 1 manifolds without focal points

If $(M,g)$ is a smooth compact rank $1$ Riemannian manifold without focal points, it is shown that the measure $\mu_{\max}$ of maximal entropy for the geodesic flow is unique. In this article, we study the statistic properties and prove that this unique measure $\mu_{\max}$ is mixing. Stronger conclusion that the geodesic flow on the unit tangent bundle $SM$ with respect to $\mu_{\max}$ is Bernoulli is acquired provided $M$ is a compact surface with genus greater than one and no focal points.