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arXiv 2303.08136cond-mat.str-elcond-mat.supr-conhep-thquant-ph
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希格斯凝聚是对称保护的拓扑相:II。$U(1)$规范理论与超导体

Higgs Condensates are Symmetry-Protected Topological Phases: II. $U(1)$ Gauge Theory and Superconductors

Ryan Thorngren, Tibor Rakovszky, Ruben Verresen, Ashvin Vishwanath

摘要:

在有间隙和保持对称的物质状态中对希格斯相进行分类是一个概念上的挑战。我们证明了$U(1)$ Higgs相是一种受保护的拓扑相,并导出了适用于动态电磁场处理的超导体的拓扑响应理论和边界反常.这推广了Verresen等人对离散规范理论的讨论,arXiv:2211.01376。我们发现,在$d$空间维度的希格斯相是在一个非平凡的SPT类保护的全球$U(1)$对称性与希格斯场,和$d-2$形式$U(1)$磁对称性,与磁单极子的情况下。在$d=2$中,这给出了一个在传统对称性之间具有混合霍尔响应的SPT,而在$d=3$中,我们得到了一个由0-形式和1-形式对称性保护的新SPT,其2+1d边界异常由超流体满足。超导体的标志性特性--电磁学的希格斯相位--可以从这个SPT响应中重现。例如,约瑟夫森效应直接来自上述边界超流体。除了这种最低限度的方法是补充朗道-金兹伯格理论,其非微扰性质是有用的情况下,波动是显着的。我们证实了这一点,通过预测的稳定性的约瑟夫森效应后,引入单极$U(1)$格点规范理论,从收费1希格斯相的限制阶段调谐导致在交界处的量子临界点。此外,这一观点揭示了意想不到的联系,例如超导体表面的持续电流是如何从广义无源泵中产生的。我们还处理部分希格斯阶段的概括,包括“2 e”凝聚在电子超导体,对应于丰富的拓扑秩序。

英文摘要:

Classifying Higgs phases within the landscape of gapped and symmetry preserving states of matter presents a conceptual challenge. We argue that $U(1)$ Higgs phases are symmetry-protected topological (SPT) phases and we derive their topological response theory and boundary anomaly -- applicable to superconductors treated with dynamical electromagnetic field. This generalizes the discussion of discrete gauge theories by Verresen et al., arXiv:2211.01376. We show that a Higgs phase in $d$ spatial dimensions is in a non-trivial SPT class protected by a global $U(1)$ symmetry associated with the Higgs field, and a $d-2$ form $U(1)$ magnetic symmetry, associated with the absence of magnetic monopoles. In $d=2$, this gives an SPT with a mixed Hall response between conventional symmetries, whereas in $d=3$ we obtain a novel SPT protected by a 0-form and 1-form symmetry whose 2+1d boundary anomaly is satisfied by a superfluid. The signature properties of superconductors -- Higgs phases for electromagnetism -- can be reproduced from this SPT response. For instance, the Josephson effect directly arises from the aforementioned boundary superfluid. In addition to this minimalist approach being complementary to Landau-Ginzburg theory, its non-perturbative nature is useful in situations where fluctuations are significant. We substantiate this by predicting the stability of the Josephson effect upon introducing monopoles in $U(1)$ lattice gauge theory, where tuning from the charge-1 Higgs phase to the confined phase leads to a quantum critical point in the junction. Furthermore, this perspective reveals unexpected connections, such as how persistent currents at the surface of a superconductor arise from generalized Thouless pumps. We also treat generalizations to partial-Higgs phases, including "2e" condensates in electronic superconductors, corresponding to symmetry-enriched topological orders.

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