最小 Kitaev 链的单次奇偶校验读出
Single-shot parity readout of a minimal Kitaev chain
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology（代尔夫特理工大学奎克与卡弗里纳米科学研究所）
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC)（马德里材料科学研究所（ICMM），西班牙高等科学研究委员会（CSIC））
- Department of Applied Physics, Eindhoven University of Technology（埃因霍温理工大学应用物理系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出基于量子电容的全局读出技术，实现了最小 Kitaev 链中 Majorana 模式联合奇偶性的实时单次判别，测得奇偶寿命超过一毫秒，解决了 Majorana 量子比特时域控制的关键读出难题。
AI中文摘要：
保护量子比特免受噪声影响是构建可靠量子计算机的关键。拓扑量子比特通过利用成对的 Majorana 零模非局域地编码量子信息，为实现这一目标提供了一条途径。这些模式形成一个共享的费米子态，其占据数——偶数或奇数——定义了编码量子比特的费米子奇偶性。至关重要的是，任何仅探测一个 Majorana 模式的测量都无法获取这一奇偶性。这反映了编码的非局域本质及其对噪声的内在保护。实现此类量子比特的一个有前景的平台是 Kitaev 链，它在通过超导体耦合的量子点中实现。即使是由两个点组成的最小链，也能承载一对 Majorana 模式，并在它们的联合奇偶性中存储量子信息。在此，我们引入一种基于量子电容的新技术来读出这一奇偶性。这种全局探针感知链的联合状态，并能够对奇偶态进行实时、单次判别。通过与同步的局域电荷传感进行比较，我们确认只有全局信号能够分辨奇偶性。我们观察到随机电报切换，并提取出超过一毫秒的奇偶寿命。这些结果确立了 Majorana 量子比特时域控制所必需的读出步骤，解决了一个长期存在的实验挑战。
英文摘要：
Protecting qubits from noise is essential for building reliable quantum computers. Topological qubits offer a route to this goal by encoding quantum information non-locally, using pairs of Majorana zero modes. These modes form a shared fermionic state whose occupation -- either even or odd -- defines the fermionic parity that encodes the qubit. Importantly, this parity can only be accessed by a measurement that couples two Majoranas to each other. A promising platform for realizing such qubits is the Kitaev chain, implemented in quantum dots coupled via superconductors. Even the minimal two-site chain hosts a pair of Majorana modes, often called poor man's Majoranas, which are spatially separated but offer limited protection compared to longer chains. Here we introduce a measurement technique that reads out their parity through quantum capacitance. Our method couples two Majoranas and resolves their parity in real time, visible as random telegraph switching with lifetimes exceeding a millisecond. Simultaneous charge sensing confirms that the two parity states are charge neutral and remain indistinguishable to a probe that does not couple the modes. These results establish the essential readout step for time-domain control of Majorana qubits, resolving a long-standing experimental challenge.
