Nonlinear Gamow vectors, shock waves and irreversibility in optically nonlocal media

TL;DR

This paper introduces a theoretical framework using nonlinear Gamow vectors to explain irreversibility in dispersive shock waves within nonlocal media, revealing fundamental limits on reversing wave evolution and linking optical phenomena to quantum irreversibility models.

Contribution

The paper develops a novel theoretical approach employing nonlinear Gamow vectors to analyze irreversibility in shock wave dynamics in nonlocal nonlinear media.

Findings

Nonlinear Gamow vectors describe shock wave irreversibility.

Irreversibility increases with nonlocality and nonlinearity.

Optical media can simulate quantum irreversible models.

Abstract

Dispersive shock waves dominate wave-breaking phenomena in Hamiltonian systems. In the absence of loss, these highly irregular and disordered waves are potentially reversible. However, no experimental evidence has been given about the possibility of inverting the dynamics of a dispersive shock wave and turn it into a regular wave-front. Nevertheless, the opposite scenario, i.e., a smooth wave generating turbulent dynamics is well studied and observed in experiments. Here we introduce a new theoretical formulation for the dynamics in a highly nonlocal and defocusing medium described by the nonlinear Schroedinger equation. Our theory unveils a mechanism that enhances the degree of irreversibility. This mechanism explains why a dispersive shock cannot be reversed in evolution even for an arbitrarirly small amount of loss. Our theory is based on the concept of nonlinear Gamow vectors, i.e., power dependent generalizations of the counter-intuitive and hereto elusive exponentially decaying states in Hamiltonian systems. We theoretically show that nonlinear Gamow vectors play a fundamental role in nonlinear Schroedinger models: they may be used as a generalized basis for describing the dynamics of the shock waves, and affect the degree of irreversibility of wave-breaking phenomena. Gamow vectors allow to analytically calculate the amount of breaking of time-reversal with a quantitative agreement with numerical solutions. We also show that a nonlocal nonlinear optical medium may act as a simulator for the experimental investigation of quantum irreversible models, as the reversed harmonic oscillator.