Parity-protected superconducting qubits offer intrinsically long coherence, but many current implementations require magnetic-flux biasing, which introduces flux noise, control overhead, and limited scalability. Here we propose a parity-protected qubit based on a gate-tunable superconductor-altermagnet-superconductor Josephson junction. Altermagnets are compensated magnets with momentum-dependent spin splitting and zero net magnetization, providing spin-dependent functionality without external magnetic fields. In the proposed junction, the two spin sectors acquire opposite phase shifts, generating two Josephson channels whose interference is controlled electrically by the chemical potential. At the tuned $0$-$π$ transition, the first Josephson harmonic is strongly suppressed while the second harmonic dominates, yielding a double-well potential with two nearly degenerate states of opposite Cooper-pair parity. For realistic gatemon-compatible parameters, we estimate coherence times of up to tens of milliseconds while maintaining fully gate-controlled qubit operations. These results establish altermagnetic Josephson junctions as a promising route toward protected superconducting qubits with local, scalable, and all-electrical control.
Phase Transitions in Disordered Altermagnetic Josephson Junctions
Hefei National Laboratory（合肥国家实验室）；School of Emerging Technology, University of Science and Technology of China（中国科学技术大学先进技术研究院）；Institute for Theoretical Physics and Astrophysics, University of Würzburg（维尔茨堡大学理论物理与天体物理研究所）
Phase-Controlled Majorana Zero Modes in Altermagnetic Topological-Insulator Josephson Junctions
Huazhong University of Science and Technology（华中科技大学）；Tsung-Dao Lee Institute（李政道研究所）；School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院）；High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院高磁场实验室）；College of Physics and Optoelectronic Engineering, Department of Physics, Jinan University（暨南大学物理与光电工程学院）；Hefei National Laboratory（合肥国家实验室）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）
Dynamical Steering and Unambiguous Signature of Majorana Corner Modes in Altermagnetic Josephson Junctions
Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University（华南师范大学物理学院）；Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University（华南师范大学前沿物理研究院）
Spin-Polarized Josephson Supercurrent in Nodeless Altermagnets
Zhejiang University（浙江大学）；Hefei National Laboratory（合肥国家实验室）；University of Science and Technology of China（中国科学技术大学）；University of Chinese Academy of Sciences（中国科学院大学）
Altermagnetic-doping interplay as a route to enhanced d-wave pairing in the Hubbard model
School of Science, Harbin Institute of Technology, Shenzhen（哈尔滨工业大学深圳校区理学院）；Department of Physics, Jiangsu University（江苏大学物理学院）；Shenzhen Key Laboratory of Advanced Functional Carbon Materials Research and Comprehensive Application（深圳市先进功能碳材料研究及综合应用重点实验室）；Institute for Materials Research, Tohoku University（东北大学材料科学研究所）
Josephson effects in the spin-triplet superconductor/altermagnet/spin-triplet superconductor junctions: the detection of the intrinsic $\bf{d}$-vector
School of Science, Qingdao University of Technology（青岛理工大学理学院）；International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料科学中心）；Hefei National Laboratory（合肥国家实验室）
Influence of Topological Edge States on the Properties of Al/Bi2Se3/Al Hybrid Josephson Devices
在超导体-拓扑绝缘体-超导体混合结中，势垒边缘态有望被保护免受背散射，产生非常规的邻近效应，并可能发出马约拉纳费米子存在的信号。这些类型的结构的邻近模式的标准必须解决一个整洁的识别可能的新实体。通过对约瑟夫森特性的系统和完整的测量，我们发现了共面Al-Bi_2Se_3-Al结中存在弹道输运的证据，并将其归因于通过拓扑边缘态的相干输运。散粒体的分流作用只影响正常的输运。这种行为在某种程度上可以被认为是普遍的，与超导电极的具体特征相当无关。通过对Shubnikov-de Haas振荡和扫描隧道光谱的比较研究，给出了与具有狄拉克色散关系的二维电子输运通道相容的实验特征。将Bi 2 Se 3薄片的尺寸减小到纳米级是在适当的制度下驱动约瑟夫森结以检测马约拉纳费米子的可能的独特特征的不可避免的步骤。
Josephson diode and spin-valve effects on the surface of altermagnet CrSb
Institute of Solid State Physics of the Russian Academy of Sciences（俄罗斯科学院固体物理研究所）；V.L. Ginzburg Research Centre for High-Temperature Superconductivity and Quantum Materials, P.N. Lebedev Physical Institute of RAS（俄罗斯科学院列别杰夫物理研究所V.L.金兹堡高温超导与量子材料研究中心）
Matrix-pairing states in the alkaline Fe-selenide superconductors: exotic Josephson junctions
多带碱性铁硒化物和最近的重费米子CeCu $_{2}$ Si $_{2}$确实具有非常规性质，它们显示出完全带隙但变号的超导性（SC）。一个双轨道的配对状态，称为$sτ_{3}$，与非平凡的矩阵结构，被提出作为一个候选人能够调和这些SC的看似矛盾的属性。出于非平凡的轨道结构的建议$sτ_{3}$状态，它具有轨道选择性配对结构，我们研究原型约瑟夫森结，其中至少有一个引线是在SC状态的这种。在两个简并轨道（带）的极限和一个简单的连接杂交形式的这些路口的分析揭示了几个显着的性能。一个是出现了无带隙的，纯粹的电子和空穴的束缚态的$sτ_{3}-N-sτ_{3}$结与任意的全球之间的相位差的铅，同样的$sτ_{3}-N-I$结。另一个是静态约瑟夫森电流的情况下，当两个引线是SC的。在这两个特征中，$sτ_{3}$结与传统的约瑟夫森结有很大的不同。我们还发现，无隙束缚态的轨道交换对称性的保护，虽然保护不是拓扑。打破这种对称性的结，如$sτ_{3}-N-s$，具有带隙的Andreev束缚态。一般来说，一旦两个轨道的简并被解除，约瑟夫森效应也会重新出现。我们支持这些结论，通过分析和数值计算结果的束缚态，以及微观计算的约瑟夫森电流。我们的研究结果表明，涉及$sτ_{3}$配对在碱性铁硒化物的结一般会有一个小的间隙，以及极大地抑制约瑟夫森电流的束缚态。
Quantum Advanced Research Center (QuARC), Consejo Superior de Investigaciones Científicas (CSIC)（量子先进研究中心，西班牙国家研究委员会）；Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC)（马德里材料科学研究所，西班牙国家研究委员会）；Universidad Autónoma de Madrid（马德里自治大学）
