Surrogate model solver for impurity-induced superconducting subgap states

Virgil V. Baran; Emil J. P. Frost; Jens Paaske

doi:10.1103/physrevb.108.l220506

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arXiv · 2307.11646

Surrogate model solver for impurity-induced superconducting subgap states

Virgil V. Baran·Emil J. P. Frost·Jens Paaske

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Abstract

A simple impurity solver is shown to capture the impurity-induced superconducting subgap states in quantitative agreement with the numerical renormalization group and quantum Monte-Carlo simulations. The solver is based on the exact diagonalization of a single-impurity Anderson model with discretized superconducting reservoirs including only a small number of effective levels. Their energies and couplings to the impurity $d$-level are chosen so as to best reproduce the Matsubara frequency dependence of the hybridization function. We provide a number of critical benchmarks and demonstrate the solvers efficiency in combination with the reduced basis method [Phys. Rev. B 107, 144503 (2023)] by calculating the phase diagram for an interacting three-terminal junction.

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Virgil V. Baran, Emil J. P. Frost, Jens Paaske. 2023-07-21. Surrogate model solver for impurity-induced superconducting subgap states. https://doi.org/10.1103/physrevb.108.l220506

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