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arXiv · 2402.18357

BCS surrogate models for floating superconductor-semiconductor hybrids

Virgil V. Baran·Jens Paaske
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Abstract

Superconductor-semiconductor hybrid devices, involving quantum dots interfaced with floating and/or grounded superconductors, have reached a level of complexity which calls for the development of versatile and numerically efficient modelling tools. Here, we propose an extension of the surrogate model solver for sub-gap states [Phys. Rev. B 108, L220506 (2023)], which is able to handle floating superconducting islands with finite charging energy. Upon eliminating all finite-size effects of the computationally demanding Richardson model approach, we achieve a more efficient way of calculating the sub-gap spectra and related observables without compromising their accuracy. We provide a number of benchmarks between the two approaches and showcase the versatility of the extended surrogate model solver by studying the stability of spin-triplet ground states in various tunable devices. The methods introduced here set the stage for reliable microscopic simulations of complex superconducting quantum circuits across all their relevant parameter regimes.

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Virgil V. Baran, Jens Paaske. 2024-05-07. BCS surrogate models for floating superconductor-semiconductor hybrids. https://doi.org/10.1103/physrevb.109.224501

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