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arXiv 2408.15080cond-mat.mes-hallcond-mat.str-elcond-mat.supr-con
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通过量子自旋耦合在“穷人的马约拉纳”中实现精细结构的压缩态保护

Squeezed state protection of fine structure in "Poor Man's Majorana" via quantum spin coupling

J. E. Sanches, L. T. Lustosa, L. S. Ricco, H. Sigurðsson, M. de Souza, M. S. Figueira, E. Marinho, A. C. Seridonio

AI总结:

本文提出一种模型,通过将量子点与量子自旋交换耦合,利用零频率处的压缩态钉扎效应,使缺乏拓扑保护的“Poor Man's Majorana”零模免受精细结构混合,从而实现对量子自旋扰动的鲁棒性保护。

摘要:

缺乏拓扑保护的“Poor Man's Majorana”[Phys. Rev. B 86, 134528 (2012)]在理论上被预测依赖于最小 Kitaev 链。随后,一对超导和无自旋量子点使该方案变得可行,并且微分电导精确指出了与此场景一致的指纹[Nature 614, 445 (2023) 和 Nature 630, 329 (2024)]。在这项工作中,我们提出了一个模型,其中一个量子点与量子自旋交换耦合时,“Poor Man's Majorana”呈现出保护特性。如果通过调节交换耦合来扰动该量子点,该 Majorana 著名的溢出行为令人惊讶地保持不变,并且仅意外地观察到精细结构的一半。事实上,“Poor Man's Majorana”零模在于将另一半在零频率处进行压缩,这迫使它被钉扎在那里,并阻止了该模式与显式精细结构的混合。我们声称,如果预期中由精细结构导致的零模不可避免的分裂意外地不存在,那么“Poor Man's Majorana”可以被认为对量子自旋具有鲁棒性。通过这种方式,它获得了保护,并且“Poor Man's Majorana”缺乏拓扑保护的范式被重新审视,将这个看似已确立的问题推向了新的方向。

英文摘要:

The "Poor Man's Majorana" [Phys. Rev. B 86, 134528 (2012)] devoid of topological protection has been theoretically predicted to rely on the minimal Kitaev chain. Afterward, a pair of superconducting and spinless quantum dots turned the proposal practicable and differential conductance pinpointed consistent fingerprints with such a scenario [Nature 614, 445 (2023) and Nature 630, 329 (2024)]. In this work, we propose a model wherein the "Poor Man's Majorana" presents protection when one of the dots is exchange coupled to a quantum spin. If this quantum dot is perturbed by tuning the exchange coupling, the well-known spill over-like behavior of this Majorana surprisingly remains unchanged, and solely half of the fine structure is unexpectedly viewed. As a matter of fact, the "Poor Man's Majorana" zero mode consists in squeezing of the other half at zero frequency, which imposes its pinning there and prevents the mixing of the mode with the explicit fine structure. We claim that if the supposed unavoidable split of the zero mode by the fine structure is unexpectedly absent, then the "Poor Man's Majorana" can be considered robust against the quantum spin. In this way, it becomes protected and the lack of topological protection paradigm of the "Poor Man's Majorana" has been revisited, pushing this seemingly well-established issue into a new direction.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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