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arXiv · 2308.14751

Probing Majorana localization in minimal Kitaev chains through a quantum dot

Rubén Seoane Souto·Athanasios Tsintzis·Martin Leijnse·Jeroen Danon
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Abstract

Artificial Kitaev chains, formed by quantum dots coupled via superconductors, have emerged as a promising platform for realizing Majorana bound states. Even a minimal Kitaev chain (a quantum dot--superconductor--quantum dot setup) can host Majorana states at discrete sweet spots. However, unambiguously identifying Majorana sweet spots in such a system is still challenging. In this work, we propose an additional dot coupled to one side of the chain as a tool to identify good sweet spots in minimal Kitaev chains. When the two Majorana states in the chain overlap, the extra dot couples to both and thus splits an even--odd ground-state degeneracy when its level is on resonance. In contrast, a ground-state degeneracy will persist for well-separated Majorana states. This difference can be used to identify points in parameter space with spatially separated Majorana states, using tunneling spectroscopy measurements. We perform a systematic analysis of different relevant situations. We show that the additional dot can help distinguishing between Majorana sweet spots and other trivial zero-energy crossings. We also characterize the different conductance patterns, which can serve as a guide for future experiments aiming to study Majorana states in minimal Kitaev chains.

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Rubén Seoane Souto, Athanasios Tsintzis, Martin Leijnse, Jeroen Danon. 2023-08-28. Probing Majorana localization in minimal Kitaev chains through a quantum dot. https://doi.org/10.1103/physrevresearch.5.043182

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