TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.18.4.120
TI  - Universal aspects of high-temperature relaxation dynamics in random spin models
PY  - 2025/04/08
UR  - https://scipost.org/SciPostPhys.18.4.120
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 18
IS  - 4
SP  - 120
A1  - Zhou, Tian-Gang
AU  - Zheng, Wei
AU  - Zhang, Pengfei
AB  - Universality is a crucial concept in modern physics, allowing us to capture the essential features of a system's behavior using a small set of parameters. In this work, we unveil universal spin relaxation dynamics in anisotropic random Heisenberg models with infinite-range interactions at high temperatures. Starting from a polarized state, the total magnetization can relax monotonically or decay with long-lived oscillations, determined by the sign of a universal single function $A=-\xi_1^2+\xi_2^2-4\xi_2\xi_3+\xi_3^2$. Here $(\xi_1,\xi_3,\xi_3)$ characterizes the anisotropy of the Heisenberg interaction. Furthermore, the oscillation shows up only for $A>0$, with frequency $\Omega \propto \sqrt{A}$. This result is derived from the Kadanoff-Baym equation under the melon diagram approximation, which is consistent with numerical solutions. Furthermore, we verify our theory and approximation using exact diagonalization, albeit for a small system size of $N=8$. Our study sheds light on the universal aspect of quantum many-body dynamics beyond low energy limit.
ER  -

@Article{10.21468/SciPostPhys.18.4.120,
	title={{Universal aspects of high-temperature relaxation dynamics in random spin models}},
	author={Tian-Gang Zhou and Wei Zheng and Pengfei Zhang},
	journal={SciPost Phys.},
	volume={18},
	pages={120},
	year={2025},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.18.4.120},
	url={https://scipost.org/10.21468/SciPostPhys.18.4.120},
}