Nonthermal fixed points in a one-dimensional antiferromagnetic spinor Bose gas

Recently, a nonthermal fixed point (NFTP) is proposed as a universal thermalization scenario [1], where a system evolving from a non-equilibrium initial state is attracted to the NTFP and shows a universal dynamical scaling law. We theoretically study quench dynamics in a one-dimensional (1D) antiferromagnetic (AF) spinor Bose gas, finding universal thermalization dynamics characterized by a NTFP induced by two types of solitons. One soliton is a magnetic soliton having a locally magnetized part, and the other is an exotic bound state of magnetic solitons, which we refer to as a Flemish string because of the twisted magnetic structure. We numerically find that the stable magnetic solitons can disappear through formation of the Flemish strings, and that the cooperative soliton dynamics through the Flemish string promotes the relaxation. Then, we elucidate the dynamical scaling regarded as a signature of the NTFP in the quench dynamics. Furthermore, studying the experiment for a trapped 1D AF Bose gas [2], we find that the universal thermalization with the NTFP appear if the applied filed is quenched more strongly compared with the experiment.
[1] J. Berges, arXiv:1503.02907 (2015).
[2] A. Vinit, E. M. Bookjans, C. A. R. Sá de Melo, and C. Raman, Phys. Rev. Lett. 110, 165301 (2013).