发表机构
West Virginia University; Clemson University（西弗吉尼亚大学; 克莱姆森大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出单侧四元组拓扑量子比特，通过SC主干连接四条马约拉纳线，将端模分裂降低约两个数量级，显著延长宇称寿命，等效于加倍线长。
AI 中文摘要
具有Rashba自旋轨道耦合并施加塞曼场的一维SM-SC混合纳米线可以在线的两端支持马约拉纳零模（MZMs）。在有限长度系统中，端模之间的残余波函数重叠会产生能量分裂。在双侧四元组量子比特中，该量子比特由一对平行的马约拉纳线组成，这些线通过中间的普通SC主干耦合，这种分裂限制了涉及两条线的马约拉纳对的宇称寿命以及量子比特的相干性，对基于测量的编织和读出操作产生不利影响。在这里，我们提出了一种由四条平行的马约拉纳线组成的单侧四元组，这些线在一个公共端通过SC主干连接。在拓扑相中，自由线端承载四个MZMs，它们定义了拓扑量子比特，而位于相对端的马约拉纳模式通过主干杂交并获得有限能量。为了研究基本的杂交机制，我们考虑一个更简单的双线子系统，即单侧四元组的一半，我们称之为双元组。在双元组中，主干或桥强烈杂交连接端的两个马约拉纳模式，并将它们移离零能量，而自由端的模式形成一个近零能量费米子。我们表明，存活的MZM对的能量分裂可以比双侧四元组中的分裂能量降低约两个数量级，从而显著延长宇称寿命。因此，单侧四元组确保了对马约拉纳重叠的抑制，其效果相当于将相应的双侧四元组的长度加倍。
英文摘要
One-dimensional SM-SC hybrid nanowires with Rashba spin-orbit coupling and applied Zeeman field can support Majorana zero modes (MZMs) at the ends of the wire. In finite-length systems, residual wave-function overlap between the end modes produces an energy splitting. In a two-sided tetron qubit, composed of a pair of parallel Majorana wires coupled by a trivial SC backbone in the middle, this splitting limits the parity lifetime associated with Majorana pairs involving both wires and the coherence of the qubit, adversely affecting measurement-based braiding and readout operations. Here, we propose a one-sided tetron made of four parallel Majorana wires connected at a common end by an SC backbone. In the topological phase, the free wire ends host four MZMs that define the topological qubit, while the Majoranas localized near the opposite ends hybridize through the backbone and acquire finite energy. To study the basic hybridization mechanism, we consider a simpler two-wire subsystem, i.e., half of a one-sided tetron, which we call a doublon. In a doublon, the backbone, or bridge, strongly hybridizes the two Majorana modes at the connected end and shifts them away from zero energy, while the modes at the free ends form a near-zero energy fermion. We show that the splitting of the surviving MZM pair can fall by about two orders of magnitude compared to the splitting energies in a two-sided tetron, thereby dramatically increasing the parity lifetimes. Thus, the one-sided tetron ensures a suppression of the Majorana overlap comparable to doubling the length of the corresponding two-sided tetron.
Comments13 pages, 10 figures
