近日，南方科技大学薛其坤团队实现了在扭曲的铜约瑟夫森结中操纵分数夏皮罗阶跃。相关论文于2025年12月15日发表在《国家科学评论》杂志上。

基于扭曲铜氧化物超导体构建的高质量约瑟夫森结，为在相对高温条件下探索基础物理问题与实现下一代超导器件提供了前所未有的机遇。然而，扭曲铜氧化物体系是否具有高温拓扑超导性仍是悬而未决的关键问题。

研究组通过深入探究其理论预测的核心特征——半整数夏皮罗阶梯，对此问题展开系统研究。实验表明，在45°扭转角的样品中确实会出现半整数夏皮罗阶梯，但该现象在热循环过程中表现出不稳定性。值得注意的是，通过施加小磁场对样品进行磁化训练，或采用大电流进行退火处理，均可诱导产生分数阶梯现象，这证实了扭曲铜氧化物体系具有可调控的电流-相位关系。

研究组进一步通过电流退火技术，成功实现了分母为奇数的分数阶梯。更重要的是，半整数阶梯的出现条件远超出拓扑超导性的理论预期范围，这更倾向于支持另一种涉及涡旋俘获机制的物理解释。该研究结果不仅警示了将半整数夏皮罗阶梯直接等同于奇异机制的风险，同时为实现在高温下具有电控可调电流-相位关系的约瑟夫森结开辟了新的技术路径。

附：英文原文

Title: Manipulating fractional Shapiro steps in twisted cuprate Josephson junctions

Author: Zhu, Yuying, Wang, Heng, Zhang, Ding, Xue, Qi-Kun

Issue&Volume: 2025-12-15

Abstract: High-quality Josephson junctions made of twisted cuprate superconductors offer unprecedented opportunities in addressing fundamental problems and realizing next-generation superconducting devices at relatively high temperatures. Whether or not the twisted cuprates possess high-temperature topological superconductivity remains an outstanding issue. Here, we tackle this problem via an in-depth study of the key predicted feature—half-integer Shapiro steps. We show that half-integer Shapiro steps do occur in samples at a twist angle of 45° but are unstable with thermal cycling. Interestingly, fractional steps can be introduced by training the sample with a small magnetic field or annealing with a large electrical current, attesting to a tunable current-phase relation (CPR) in twisted cuprates. We extend the current annealing to realize fractional steps with odd denominators too. Furthermore, half-integer steps can be induced in the regime that is well beyond the expectation of topological superconductivity, favoring an alternative mechanism involving trapped vortices. Our results not only caution the direct association of half-integer Shapiro steps with the exotic mechanism but also open a distinct pathway toward a Josephson junction with electrically tunable CPR at high temperatures.

DOI: 10.1093/nsr/nwaf569

Source: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaf569/8380056searchresult=1