arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.4846cond-mat.stat-mechcond-mat.str-el
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临界一维系统中的局域量子猝灭:纠缠、洛什卡回声和光锥效应

Local quantum quenches in critical one-dimensional systems: entanglement, the Loschmidt echo, and light-cone effects

Jean-Marie Stéphan, Jérôme Dubail

摘要:

我们使用共形场论(CFT)技术研究了一般量子临界一维系统中的一种特殊类型的局部猝灭,并提供了自由费米子系统中结果的数值检验。系统最初被分割成两个子系统$A$和$B$,它们在时间$t=0$粘合在一起。利用Calabrese和Cardy的结果,进一步推广了$A$和$B$两部分之间的纠缠熵.我们还详细研究了(对数)Loschirton回波(LLE)。对于有限大小的系统,这两个量在标度极限中(几乎)是周期性的,并表现出惊人的光锥效应。虽然这两个量在猝灭后立即表现出类似的行为--即EE的$c/3 \log t$和LLE的$c/4 \log t$--,但一旦猝灭发射的激发在边界上反弹并在同一子系统$A$(或$B$)内演化,我们就会观察到一些差异。因此,EE的衰变是非普遍的,正如Alfredler和Peschel所注意到的那样。相反,我们发现LLE的演化对模型的非普适细节不像EE那么敏感,并且仍然可以通过我们的CFT预测准确描述。为了进一步探索这些光锥效应,我们还介绍了一个变种的Loschillo回声专门构造检测激发后发出的淬火。

英文摘要:

We study a particular type of local quench in a generic quantum critical one-dimensional system, using conformal field theory (CFT) techniques, and providing numerical checks of the results in free fermion systems. The system is initially cut into two subsystems $A$ and $B$ which are glued together at time $t=0$. We study the entanglement entropy (EE) between the two parts $A$ and $B$, using previous results by Calabrese and Cardy, and further extending them. We also study in detail the (logarithmic) Loschmidt echo (LLE). For finite-size systems both quantities turn out to be (almost) periodic in the scaling limit, and exhibit striking light-cone effects. While these two quantities behave similarly immediately after the quench---namely as $c/3 \log t$ for the EE and $c/4 \log t$ for the LLE---, we observe some discrepancy once the excitations emitted by the quench bounce on the boundary and evolve within the same subsystem $A$ (or $B$). The decay of the EE is then non-universal, as noticed by Eisler and Peschel. On the contrary, we find that the evolution of the LLE is less sensitive than the EE to non-universal details of the model, and is still accurately described by our CFT prediction. To further probe these light-cone effects, we also introduce a variant of the Loschmidt echo specifically constructed to detect the excitations emitted just after the quench.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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