Replica Symmetry Breaking in the Internal Motion Within Ultrafast Dissipative Optical Soliton Molecules

Replica symmetry breaking, a central concept in statistical physics, has been reported in a variety of photonic platforms dominated by high effective dimensionality or disorder, whereas its manifestation in reduced optical systems with well‐defined internal degrees of freedom has received little attention. Dissipative optical soliton molecules provide a prototypical nonlinear system in which internal degrees of freedom, such as interpulse separation, are well‐defined and experimentally accessible. By combining a mode‐locked fiber laser with real‐time balanced optical correlation measurements offering sub‐femtosecond temporal sensitivity, we directly resolve shot‐to‐shot fluctuations of the interpulse separation across nominally identical experimental replicas. Analysis of the resulting correlation structure reveals clear deviations from replica symmetry in aperiodic internal dynamical regimes. Complementary numerical simulations reproduce the experimental observations and further demonstrate that detrending the sliding‐phase dynamics serves to isolate the fluctuation‐driven components of the internal motion, thereby revealing consistent symmetry‐breaking signatures across different internal degrees of freedom. These results identify dissipative soliton molecules as a highly controllable photonic platform for investigating statistical symmetry breaking and collective internal dynamics in reduced‐dimensional nonlinear systems.