School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, Yorkshire LS2 9JT, UK.
Nat Commun. 2017 Apr 5;8:14926. doi: 10.1038/ncomms14926.
Interacting bosons or fermions give rise to some of the most fascinating phases of matter, including high-temperature superconductivity, the fractional quantum Hall effect, quantum spin liquids and Mott insulators. Although these systems are promising for technological applications, they also present conceptual challenges, as they require approaches beyond mean-field and perturbation theory. Here we develop a general framework for identifying the free theory that is closest to a given interacting model in terms of their ground-state correlations. Moreover, we quantify the distance between them using the entanglement spectrum. When this interaction distance is small, the optimal free theory provides an effective description of the low-energy physics of the interacting model. Our construction of the optimal free model is non-perturbative in nature; thus, it offers a theoretical framework for investigating strongly correlated systems.
相互作用的玻色子或费米子会导致物质的一些最迷人的相，包括高温超导、分数量子霍尔效应、量子自旋液体和莫特绝缘体。尽管这些系统在技术应用方面很有前景，但它们也提出了概念上的挑战，因为它们需要超越平均场和微扰理论的方法。在这里，我们开发了一个通用框架，用于根据它们的基态相关性来确定与给定相互作用模型最接近的自由理论。此外，我们还使用纠缠谱来量化它们之间的距离。当这个相互作用距离很小时，最优的自由理论为相互作用模型的低能物理提供了有效的描述。我们对最优自由模型的构造在本质上是非微扰的；因此，它为研究强关联系统提供了一个理论框架。
