Spontaneous symmetry breaking induced by nonlinear interaction in a coupler supported by fractional diffraction

Abstract

In this paper we introduce a one-dimensional model of coupled fractional nonlinear Schrödinger equations with a double-well potential applied to one component. This study examines ground state (GS) solitons, observing spontaneous symmetry breaking (SSB) in both the actuated field and the partner component due to nonlinear coupling. Numerical simulations reveal symmetric and asymmetric profiles arising from a slightly asymmetric initial condition. Asymmetry is influenced by nonlinearities, potential depth, and coupling strength, with self-focusing systems favoring greater asymmetry. Fractional diffraction affects the amplitude and localization of symmetric profiles and the stability of asymmetric ones. We identify critical Lévy index values for generating coupled GS solitons. Stability analysis of unstable, centrally asymmetric GS solitons demonstrates oscillatory dynamics, providing new insights into SSB in fractional systems and half-trapped solitons.