Mithun Thudiyangal, Danieli Carlo, Fistul M V, Altshuler B L, Flach Sergej
Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-4515, USA.
Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34051, Korea.
Phys Rev E. 2021 Jul;104(1-1):014218. doi: 10.1103/PhysRevE.104.014218.
Weakly nonintegrable many-body systems can restore ergodicity in distinctive ways depending on the range of the interaction network in action space. Action resonances seed chaotic dynamics into the networks. Long-range networks provide well connected resonances with ergodization controlled by the individual resonance chaos time scales. Short-range networks instead yield a dramatic slowing down of ergodization in action space, and lead to rare resonance diffusion. We use Josephson junction chains as a paradigmatic study case. We exploit finite time average distributions to characterize the thermalizing dynamics of actions. We identify an action resonance diffusion regime responsible for the slowing down. We extract the diffusion coefficient of that slow process and measure its dependence on the proximity to the integrable limit. Independent measures of correlation functions confirm our findings. The observed fragile diffusion is relying on weakly chaotic dynamics in spatially isolated action resonances. It can be suppressed, and ergodization delayed, by adding weak action noise, as a proof of concept.
弱非可积多体系统可以根据作用空间中相互作用网络的范围，以独特的方式恢复遍历性。作用共振将混沌动力学引入网络。长程网络提供连接良好的共振，其遍历性由各个共振混沌时间尺度控制。相反，短程网络会导致作用空间中遍历性显著减慢，并导致罕见的共振扩散。我们将约瑟夫森结链用作典型研究案例。我们利用有限时间平均分布来表征作用的热化动力学。我们确定了一个导致减慢的作用共振扩散区域。我们提取了该慢过程的扩散系数，并测量其对接近可积极限的依赖性。相关函数的独立测量结果证实了我们的发现。观察到的脆弱扩散依赖于空间孤立的作用共振中的弱混沌动力学。作为概念验证，通过添加弱作用噪声可以抑制它并延迟遍历性。
