Isolated many-body systems far from equilibrium may exhibit scaling dynamics with universal exponents indicating the proximity of the time evolution to a nonthermal fixed point. We find universal dynamics connected with the occurrence of extreme wave excitations in the mutually coupled magnetic components of a spinor gas which propagate in an effectively random potential. The frequency of these rogue waves is affected by the time-varying spatial correlation length of the potential, giving rise to an additional exponent δc≃1/3 for temporal scaling, which is different from the exponent βV≃1/4 characterizing the scaling of the correlation length ℓV∼tβV in time. As a result of the caustics, i.e., focusing events, real-time instanton defects appear in the Larmor phase of the spin-1 system as vortices in space and time. The temporal correlations governing the instanton occurrence frequency scale as tδI. This suggests that the universality class of a nonthermal fixed point could be characterized by different, mutually related exponents defining the evolution in time and space, respectively. Our results have a strong relevance for understanding pattern coarsening from first principles and potential implications for dynamics ranging from the early Universe to geophysical dynamics and microphysics.
I. Siovitz, S. Lannig, Y. Deller, H. Strobel, M.K. Oberthaler, T. Gasenzer, “Universal Dynamics of Rogue Waves in a Quenched Spinor Bose Condensate”, Phys. Rev. Lett. 131, 183402 (2023).
Related to Project A04