AI 中文总结
本研究基于镓掺杂锗的超导性，采用完全外延法制备了晶态IV族约瑟夫森结，其具备原子级尖锐界面等优势，为低无序、CMOS兼容的超导量子比特提供了新方案。
AI 中文摘要
传统超导量子电子学依赖成熟的Al/AlO$_{x}$约瑟夫森结，其中作为弱连接的AlO$_{x}$为非晶态，被认为存在限制相干性的二能级系统。晶态约瑟夫森结具有原子级有序的界面质量，但受限于复杂的制备工艺和外延生长的本征不对称性。本文展示了一种基于镓掺杂锗超导性的完全外延方法，可实现通过分子束外延原位生长的全约瑟夫森结。这些器件具有原子级尖锐界面和晶态弱连接，在超短 regime 中呈现强约瑟夫森耦合。我们观察到外加磁场下开关电流的非常规增强，将其归因于来自Al接触的准粒子辅助热化过程。该平台结合了结构相干性、制备简便性和可扩展性，为合并元件transmon架构中低无序、CMOS兼容的超导量子比特提供了有前景的途径。
英文摘要
Conventional superconducting quantum electronics rely on well-established Josephson junctions made of Al/AlO$_{x}$ where the weak link AlO$_{x}$ is amorphous and is believed to host two-level systems that limit coherence. Crystalline Josephson junctions exhibit atomically ordered interface quality but remain constrained by complex fabrication and intrinsic asymmetry of epitaxial growth. Here, we demonstrate a fully epitaxial approach based on superconductivity in gallium-doped germanium, enabling the realization of Josephson junctions entirely grown in situ by molecular beam epitaxy. These devices feature atomically sharp interfaces and crystalline weak links, resulting in strong Josephson coupling in the ultra-short regime. We observe an unconventional enhancement of the switching current under applied magnetic field, which we attribute to quasiparticle-assisted thermalization processes from the Al contacts. This platform combines structural coherence, fabrication simplicity, and scalability, offering a promising route toward low-disorder, CMOS-compatible superconducting qubits in a merged element transmon architecture.
