arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2001.06586cond-mat.str-elcond-mat.supr-con
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Yukawa-SYK模型与自调谐量子临界性

Yukawa-SYK model and Self-tuned Quantum Criticality

Gaopei Pan, Wei Wang, Andrew Davis, Yuxuan Wang, Zi Yang Meng

摘要:

非费米液体(NFL)是一类没有长寿命准粒子激发的强相互作用无带隙费米系统。NFL模型的一个重要组成部分是在量子临界点(QCP)附近耦合到软玻色子波动的巡回费米子,并且被广泛认为可以捕获许多非常规超导体的基本物理。然而,在这种系统中,以格林函数中的幂律形式为特征的典型NFL行为的直接观察在数值上是难以捉摸的。在这里,我们考虑一个Sachdev-Ye-Kitaev(SYK)类模型与临界玻色子和费米子之间的随机汤川相互作用(称为汤川-SYK模型)。我们表明,它是免疫的负号问题,因此可以通过大规模的量子蒙特卡罗模拟超出大$N$限制解析方法可以精确地解决。我们的模拟表明Yukawa-SYK模型具有“自调谐量子临界性”,即系统是临界的,与玻色子裸质量无关。我们把这些结果在有限的$N$测试,我们的无偏数值揭示了这些奇异的量子临界NFL属性的明确证据-费米子和玻色子的格林函数的幂律行为-这推动了临界普朗克金属和非常规超导体的理论理解。

英文摘要:

Non-Fermi liquids (NFL) are a class of strongly interacting gapless fermionic systems without long-lived quasiparticle excitations. An important group of NFL model features itinerant fermions coupled to soft bosonic fluctuations near a quantum-critical point (QCP), and are widely believed to capture the essential physics of many unconventional superconductors. However numerically the direct observation of a canonical NFL behavior in such systems, characterized by a power-law form in the Green's function, has been elusive. Here we consider a Sachdev-Ye-Kitaev (SYK)-like model with random Yukawa interaction between critical bosons and fermions (dubbed Yukawa-SYK model). We show it is immune from minus-sign problem and hence can be solved exactly via large-scale quantum Monte Carlo simulation beyond the large-$N$ limit accessible to analytical approaches. Our simulation demonstrates the Yukawa-SYK model features "self-tuned quantum criticality", namely the system is critical independent of the bosonic bare mass. We put these results to test at finite $N$, and our unbiased numerics reveal clear evidence of these exotic quantum-critical NFL properties -- the power-law behavior in Green's function of fermions and bosons -- which propels the theoretical understanding of critical Planckian metals and unconventional superconductors.

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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