发表机构
Haas School of Business, University of California, Berkeley（加州大学伯克利分校哈斯商学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过微观散射模型和系综统计，揭示多端约瑟夫森结中成对电流近似的误差受费米能级附近法区模式控制，栅极失谐可显著抑制非成对电流，实现高精度两端耦合描述。
AI 中文摘要
多端约瑟夫森结中，一个弱连接耦合三个或更多超导体，这类结被研究作为拓扑安德烈夫能带、多对超电流和可调电路元件的宿主。它们的电流既被建模为两端耦合的成对网络，也通过真正的多端过程（如四重态）来建模。我们探究成对描述的准确度以及什么控制其误差。在平面结的微观散射模型中，我们将精确电流与最佳成对近似进行比较，该近似允许任意非正弦耦合。在无序三端和四端结的系综中，成对项捕获了几乎所有的能量变化，但中位电流误差范围从8.0%到21.2%，约为能量误差的两倍，因为电流更强烈地加权多端谐波。设计的器件将比较扩展到十六端。我们识别出一种控制该误差的机制。费米能级附近的一个法区模式耦合到三个或更多终端，产生大的非成对电流，通过栅极失谐可抑制它们。仅移动这一从常态性质中选出的模式，即可预测八个三端和四端器件中误差的栅极依赖性，而无需拟合电流。两个干净器件中的有限能隙计算证实了从共振附近的数十个百分点下降到低于一个百分点。一个解析单能级模型给出了任意终端数下成对准确性的充分失谐条件。因此，平面结继承了量子点中已知的共振和共隧穿区域，常态性质识别出在这两者之间选择的模式。
英文摘要
Multiterminal Josephson junctions, in which one weak link couples three or more superconductors, are studied as hosts of topological Andreev bands, multi-pair supercurrents and tunable circuit elements. Their currents are modeled both as pairwise networks of two-terminal couplings and through genuinely multiterminal processes such as quartets. We ask how accurate the pairwise description is and what controls its error. In a microscopic scattering model of planar junctions, we compare exact currents with the best pairwise approximation, which allows arbitrary nonsinusoidal couplings. In ensembles of disordered three- and four-terminal junctions, the pairwise terms capture nearly all of the energy variation, yet the median current error ranges from 8.0 to 21.2 percent, about twice the energy error, because currents weigh the multiterminal harmonics more strongly. Designed devices extend the comparison to sixteen terminals. We identify a mechanism that controls this error. A normal-region mode near the Fermi level that couples to three or more terminals produces large nonpairwise currents, and detuning it with a gate suppresses them. Shifting only this mode, selected from normal-state properties, predicts the gate dependence of the error in eight three- and four-terminal devices without fitting currents. Finite-gap calculations in two clean devices confirm a drop from tens of percent near resonance to below one percent. An analytic single-level model gives a sufficient detuning for pairwise accuracy at any terminal count. Planar junctions thus inherit the resonant and cotunneling regimes known from quantum dots, and normal-state properties identify the mode that selects between them.
Comments42 pages (12-page main text plus Supplemental Material), 20 figures, 11 tables
