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arXiv 2303.02415cond-mat.dis-nncond-mat.mtrl-sciquant-ph
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具有可调射程相互作用的无序自旋链中的纠缠熵增长

Entanglement Entropy Growth in Disordered Spin Chains with Tunable Range Interactions

Youcef Mohdeb, Javad Vahedi, Ravindra N. Bhatt, Stephan Haas, Stefan Kettemann

摘要:

无序多体量子系统在全局量子猝灭后的非平衡动力学揭示了关于相互作用和无序之间竞争的重要见解,特别是对多体局域化(MBL)产生了深刻的见解。然而,在长程相互作用自旋链中键随机性对量子猝灭动力学的实验相关影响迄今尚未被研究。在这封信中,我们研究了一个量子自旋链的纠缠熵增长后,全球淬火随机放置的自旋和远程可调的相互作用衰减与功率$α$的距离。使用强无序重整化群(SDRG)的动力学版本,我们发现$α>α_c$的纠缠熵随时间的几何增长,并变得更小,随着更大的$α$为$S(t) = S_p \ln(t)/(2α)$。给你,$S_p= 2 \ln2 -1$。我们使用数值精确对角化(ED)模拟来验证我们的结果为系统的大小高达$ N\sim 16$自旋,产生足够大的$α> α_c \approx 1.8$良好的协议。对于$α<α_c$,我们发现纠缠熵随时间呈幂律增长,$S(t)\sim t^{γ(α)}$和$0<γ(α)<1$是相互作用指数$α$的衰减函数。

英文摘要:

The non-equilibrium dynamics of disordered many-body quantum systems after a global quantum quench unveils important insights about the competition between interactions and disorder, yielding in particular an insightful perspective on many body localization (MBL). Still, the experimentally relevant effect of bond randomness in long-range interacting spin chains on the quantum quench dynamics have so far not been investigated. In this letter, we examine the entanglement entropy growth after a global quench in a quantum spin chain with randomly placed spins and long-range tunable interactions decaying with distance with power $α$. Using a dynamical version of the strong disorder renormalization group (SDRG) we find for $α>α_c$ that the entanglement entropy grows logarithmically with time and becomes smaller with larger $α$ as $S(t) = S_p \ln(t)/(2α)$. Here, $S_p= 2 \ln2 -1$. We use numerical exact diagonalization (ED) simulations to verify our results for system sizes up to $ N\sim 16$ spins, yielding good agreement for sufficiently large $α> α_c \approx 1.8$. For $α<α_c$, we find that the entanglement entropy grows as a power-law with time, $S(t)\sim t^{γ(α)}$ with $0<γ(α)<1$ a decaying function of the interaction exponent $α$.

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