Coraiola Marco, Haxell Daniel Z, Sabonis Deividas, Weisbrich Hannes, Svetogorov Aleksandr E, Hinderling Manuel, Ten Kate Sofieke C, Cheah Erik, Krizek Filip, Schott Rüdiger, Wegscheider Werner, Cuevas Juan Carlos, Belzig Wolfgang, Nichele Fabrizio
IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland.
Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany.
Nat Commun. 2023 Oct 25;14(1):6784. doi: 10.1038/s41467-023-42356-6.
In hybrid Josephson junctions with three or more superconducting terminals coupled to a semiconducting region, Andreev bound states may form unconventional energy band structures, or Andreev matter, which are engineered by controlling superconducting phase differences. Here we report tunnelling spectroscopy measurements of three-terminal Josephson junctions realised in an InAs/Al heterostructure. The three terminals are connected to form two loops, enabling independent control over two phase differences and access to a synthetic Andreev band structure in the two-dimensional phase space. Our results demonstrate a phase-controlled Andreev molecule, originating from two discrete Andreev levels that spatially overlap and hybridise. Signatures of hybridisation are observed in the form of avoided crossings in the spectrum and band structure anisotropies in the phase space, all explained by a numerical model. Future extensions of this work could focus on addressing spin-resolved energy levels, ground state fermion parity transitions and Weyl bands in multiterminal geometries.
在具有三个或更多超导端子并耦合到半导体区域的混合约瑟夫森结中，安德列夫束缚态可能形成非常规的能带结构，即安德列夫物质，其可通过控制超导相位差来设计。在此，我们报告了在InAs/Al异质结构中实现的三端约瑟夫森结的隧穿光谱测量结果。三个端子相连形成两个回路，从而能够独立控制两个相位差，并在二维相空间中获得合成安德列夫能带结构。我们的结果展示了一种相位控制的安德列夫分子，它源自两个空间重叠并杂化的离散安德列夫能级。在光谱中的避免交叉以及相空间中的能带结构各向异性形式中观察到了杂化特征，所有这些都由一个数值模型解释。这项工作未来的扩展可以集中在解决多端几何结构中的自旋分辨能级、基态费米子奇偶性转变和外尔能带问题上。
