连续统中的相位控制准束缚态与马约拉纳量子点纳米结构中的热电增强
Phase-controlled quasi-bound states in the continuum and thermoelectric enhancement in Majorana-quantum-dot nanostructures
AI总结：
研究马约拉纳零模与连续统中束缚态相互作用对交叉条形量子点热电响应的影响，用格林函数等方法分析，发现对称性破缺等可调控热电响应，超导相位控制效果显著，确定其为调控拓扑混合纳米结构电子响应的有效手段。
AI中文摘要：
我们研究了马约拉纳零模（MZMs）与连续统中的束缚态（BICs）之间的相互作用如何控制与两条拓扑超导纳米线耦合的交叉条形量子点（QD）的电子热电响应。利用格林函数形式、精确的线性响应能量积分及其低温索末菲展开，分析了系统的光谱和热电特性。结果表明，对称性破缺将BICs转变为准BICs，使其对电和热传输有贡献，从而产生有限的热电响应。不同的马约拉纳内耦合强度导致的纳米线长度不等，仅使$ZT_{el}$有适度增强，而量子点能级失谐使$ZT_{el}$增加约一个数量级。超导相位控制产生更强的增强，通过二次传输零点和明显违反维德曼 - 弗兰兹定律，使$ZT_{el}\simeq0.75$。低温下$ZT^{max}_{el}\simeq0.755$和$\mathscr{L} /\mathscr{L}_{0} = 21/5$是这种二次反共振的普遍结果。我们的结果建立了马约拉纳耦合干涉结构的相位可调热电特征，并将超导相位控制确定为工程拓扑混合纳米结构电子响应的有效手段。
英文摘要：
We investigate how the interplay between Majorana zero modes (MZMs) and bound states in the continuum (BICs) governs the electronic thermoelectric response of a crossbar-shaped quantum dot (QD) coupled to two topological-superconductor nanowires. Using the Green-function formalism, exact linear-response energy integrals, and their low-temperature Sommerfeld expansion, we analyze the spectral and thermoelectric properties of the system. We show that symmetry breaking converts BICs into quasi-BICs, allowing them to contribute to electrical and thermal transport and thereby generate a finite thermoelectric response. While unequal nanowire lengths, reflected in different intra-Majorana coupling strengths, produce only a modest enhancement of $ZT_{el}$, detuning the QD level increases $ZT_{el}$ by approximately one order of magnitude. Superconducting-phase control produces a much stronger enhancement, reaching $ZT_{el} \simeq 0.75$ through a quadratic transmission zero and a pronounced violation of the Wiedemann-Franz law. The low-temperature values $ZT^{max}_{el} \simeq 0.755$ and $\mathscr{L} /\mathscr{L}_{0} = 21/5$ are universal consequences of this quadratic antiresonance. Our results establish phase-tunable thermoelectric signatures of the Majorana-coupled interference structure and identify superconducting-phase control as an efficient means of engineering the electronic response of topological hybrid nanostructures.
