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arXiv 2402.07575cond-mat.mes-hall
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量子点阵列中的磁通可调 Kitaev 链

Flux-tunable Kitaev chain in a quantum dot array

Juan Daniel Torres Luna, A. Mert Bozkurt, Michael Wimmer, Chun-Xiao Liu

AI总结:

本文提出利用短 Josephson 结中的 Andreev 束缚态介导量子点间的超导与正常耦合,通过相位差和不对称性将最小 Kitaev 链调至强耦合区,并确定 π 相位为增强能隙和鲁棒性的最优甜点。

摘要:

在半导体-超导体混合结构中,通过 Andreev 束缚态连接量子点,为构建 Kitaev 链提供了平台。有趣的是,在双量子点中,当系统被精细调节到超导耦合与正常耦合强度相等的“甜点”时,可以涌现出一对“穷人版”Majorana 零模。对 Andreev 束缚态的调控对于实现这一点至关重要,通常通过改变其化学势来实现。在本工作中,我们提出利用短 Josephson 结中的 Andreev 束缚态来同时介导两种耦合,其比值可通过结上的相位差进行调节。这样,一个最小的 Kitaev 链就可以通过改变相位和结的不对称性,轻松调节到强耦合区,甚至无需改变量子点-混合结构的耦合强度。此外,我们确定了在 $π$ 相位处存在一个最优甜点,能够增强激发能隙并提高对相位涨落的鲁棒性。我们的方案为实现基于量子点的 Kitaev 链引入了一种新的器件平台和新的调节方法。

英文摘要:

Connecting quantum dots through Andreev bound states in a semiconductor-superconductor hybrid provides a platform to create a Kitaev chain. Interestingly, in a double quantum dot, a pair of poor man's Majorana zero modes can emerge when the system is fine-tuned to a sweet spot, where superconducting and normal couplings are equal in magnitude. Control of the Andreev bound states is crucial for achieving this, usually implemented by varying its chemical potential. In this work, we propose using Andreev bound states in a short Josephson junction to mediate both types of couplings, with the ratio tunable by the phase difference across the junction. Now a minimal Kitaev chain can be easily tuned into the strong coupling regime by varying the phase and junction asymmetry, even without changing the dot-hybrid coupling strength. Furthermore, we identify an optimal sweet spot at $π$ phase, enhancing the excitation gap and robustness against phase fluctuations. Our proposal introduces a new device platform and a new tuning method for realizing quantum-dot-based Kitaev chains.

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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