Persistence of Invariant Tori for Stochastic Nonlinear Schr\"{o}dinger in the Sense of Most Probable Paths

TL;DR

This paper extends KAM theory to stochastic nonlinear Schrödinger equations on infinite lattices, demonstrating the persistence of invariant tori and analyzing the system's most probable paths and deviations under stochastic perturbations.

Contribution

It provides an abstract framework for stochastic Hamiltonian systems, constructs the Onsager-Machlup functional, and proves the persistence of invariant tori with a probabilistic stability analysis.

Findings

Persistence of low-dimensional invariant tori under stochastic perturbations

Construction of the Onsager-Machlup functional for infinite lattice systems

Derivation of a large deviation principle and rate function for system trajectories

Abstract

This paper investigates the application of KAM theory to the stochastic nonlinear Schr\"{o}dinger equation on infinite lattices, focusing on the stability of low-dimensional invariant tori in the sense of most probable paths. For generality, we provide an abstract proof within the framework of stochastic Hamiltonian systems on infinite lattices. We begin by constructing the Onsager-Machlup functional for these systems in a weighted infinite sequence space. Using the Euler-Lagrange equation, we identify the most probable transition path of the system's trajectory under stochastic perturbations. Additionally, we establish a large deviation principle for the system and derive a rate function that quantifies the deviation of the system's trajectory from the most probable path, especially in rare events. Combining this with classical KAM theory for the nonlinear Schr\"{o}dinger equation, we demonstrate the persistence of low-dimensional invariant tori under small deterministic and stochastic perturbations. Furthermore, we prove that the probability of the system's trajectory deviating from these tori can be described by the derived rate function, providing a new probabilistic framework for understanding the stability of stochastic Hamiltonian systems on infinite lattices.