Topology, like symmetry, is a fundamental concept in understanding general properties of physical systems. In condensed matter, nontrivial topology may manifest itself as singular features in the energy spectrum or the quantization of electrical properties such as conductance and magnetic flux. Using microwave spectroscopy, we determine that a superconducting circuit with three Josephson tunnel junctions in parallel can possess degeneracies indicative of nontrivial topology. We identify three topological invariants, one of which is related to a hidden quantum mechanical supersymmetry. Measurements show that devices fabricated in different topological regimes fall on a simple phase diagram, which should be robust to junction imperfections and geometric inductance. Josephson tunnel junction circuits, which are readily fabricated with conventional microlithography techniques, allow access to a wide range of topological systems that may have no condensed matter analog. Notable spectral features of these circuits, such as degeneracies and flat bands, may find use in quantum information, sensing, and metrology. Published by the American Physical Society 2024

中文翻译：

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超导电路中非平凡拓扑的光谱特征


拓扑与对称性一样，是理解物理系统一般属性的基本概念。在凝聚态中，非平凡拓扑可能表现为能谱中的奇异特征或电导和磁通量等电特性的量子化。使用微波光谱学，我们确定具有三个并联的约瑟夫森隧道结的超导电路可以具有指示非平凡拓扑的简并性。我们确定了三个拓扑不变量，其中一个与隐藏的量子力学超对称性有关。测量表明，在不同拓扑结构中制造的器件位于简单的相图上，该相图应该对结缺陷和几何电感具有鲁棒性。Josephson 隧道结电路很容易用传统的微光刻技术制造，允许访问可能没有凝聚态类似物的各种拓扑系统。这些电路的显着光谱特征，例如简并和平坦带，可能用于量子信息、传感和计量学。 美国物理学会 2024 年出版