Invariant Gibbs measures for the one-dimensional quintic nonlinear Schrödinger equation in infinite volume
Bjoern Bringmann, Gigliola Staffilani
TL;DR
The paper proves the invariance of the infinite-volume Gibbs measure for the defocusing 1D quintic nonlinear Schrödinger equation on the real line by extending Bourgain’s periodic-infinite-volume framework to $p=5$. A key advance is a growth estimate for the infinite-volume $\Phi^{p+1}_1$-measures obtained via stochastic quantization in the Hairer–Steele scheme, yielding uniform exponential integrability and $L^{\infty}$-control. The authors then construct a quantitative coupling between finite-volume Gibbs measures $\mu_L$ and the infinite-volume limit $\mu$, and use measure invariance together with uniform a priori estimates to show that periodic solutions converge to a global, invariant limit $u$ with Law$(u(t))=\mu$ for all times. The result broadens the invariant Gibbs-measure program to higher nonlinearity in one dimension and highlights the utility of stochastic quantization and quantitative Skorokhod couplings in infinite-volume dispersive PDEs.
Abstract
We prove the invariance of the Gibbs measure for the defocusing quintic nonlinear Schrödinger equation on the real line. This builds on earlier work by Bourgain, who treated the cubic nonlinearity. The key new ingredient is a growth estimate for the infinite-volume $Φ^{p+1}_1$-measures, which is proven via the stochastic quantization method.
