发表机构
Technische Universität Braunschweig; Julius-Maximilians-Universität Würzburg（布伦瑞克工业大学; 维尔茨堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过精确对角化分析并联双量子点约瑟夫森结，发现轨道通量和隧穿宇称控制单重态-三重态竞争，产生通量可调的整流效应，二极管效率接近40%，并在中间温度下增强临界电流不对称性。
AI 中文摘要
在相互作用的纳米结构中，当正负临界电流探测依赖于相位的多体谱中不等价的部分时，可以产生非互易超电流。我们在具有强点内库仑排斥的并联双量子点约瑟夫森结中研究这一机制，其中局域和非局域库珀对转移共存。利用包含显式超导轨道的零带宽哈密顿量的精确对角化，我们表明轨道通量和规范不变的隧穿符号宇称控制局域约瑟夫森过程与非局域交换之间的干涉。对于失谐的量子点，这产生通量可调的单重态、三重态和二重态基态谱分支以及两个整流区域。在具有单占据量子点的电荷扇区[(1,1)扇区]的边界附近，二重态分支与单重态或三重态分支竞争，产生接近40%的二极管效率。在三重态主导的(1,1)扇区内，即使两个临界电流极值都位于类三重态分支上，附近的单重态交叉也不对称地重塑基态包络，产生约10-15%的更宽响应。有限温度通常抑制电荷交叉整流，然而，对于中间温度，我们发现三重态区域中归一化效率和绝对临界电流不对称性均得到增强。这些结果确立了依赖于相位的多体分支竞争作为对栅极、通量和隧穿宇称敏感的约瑟夫森非互易性来源。
英文摘要
Nonreciprocal supercurrents in interacting nanostructures can arise when the positive and negative critical currents probe inequivalent portions of a phase-dependent many-body spectrum. We study this mechanism in a parallel double-quantum-dot Josephson junction with strong intradot Coulomb repulsion, where local and non-local Cooper-pair transfer coexist. Using exact diagonalization of a zero-bandwidth Hamiltonian with explicit superconducting orbitals, we show that orbital flux and the gauge-invariant tunnel-sign parity control the interference between local Josephson processes and non-local exchange. For detuned dots, this produces flux-tunable singlet, triplet, and doublet ground-state spectral branches and two rectification regimes. Near the boundaries of the charge sector with singly occupied dots [(1,1) sector], doublet branches compete with singlet or triplet branches, yielding diode efficiencies approaching 40%. Within the triplet-dominated (1,1) sector, nearby singlet crossings asymmetrically reshape the ground-state envelope even when both critical-current extrema lie on the triplet-like branch, producing a broader response of order 10-15%. Finite temperature generally suppresses charge-crossover rectification, however, for intermediate temperatures we find an enhancement of both the normalized efficiency and the absolute critical-current asymmetry in the triplet regime. These results establish phase-dependent many-body branch competition as a gate-, flux-, and tunnel-parity-sensitive source of Josephson nonreciprocity.
Comments19 pages, 16 figures, comments are welcome
