Although signatures of superconductivity in Dirac semimetals have been reported, for instance by applying pressure or using point contacts, our understanding of the topological aspects of Dirac semimetal superconductivity is still developing. Here, we utilize nanoscale phase-sensitive junction technology to induce superconductivity in the Dirac semimetal Bi_1−xSb_x. Our radiofrequency irradiation experiments then reveal a significant contribution of 4π-periodic Andreev bound states to the supercurrent in Nb–Bi_0.97Sb_0.03–Nb Josephson junctions. The conditions for a substantial 4π contribution to the supercurrent are favourable because of the Dirac cone’s very broad transmission resonances and a measurement frequency faster than the quasiparticle poisoning rate. In addition, we show that a magnetic field applied in the plane of the junction allows tuning of the Josephson junctions from 0 to π regimes. Our results open the technologically appealing avenue of employing the topological bulk properties of Dirac semimetals for topological superconductivity research and topological quantum computer development.

尽管已经报道了狄拉克半金属中超导电性的特征，例如通过施加压力或使用点接触的方法，但我们对狄拉克半金属超导电性拓扑方面的理解仍在发展中。在这里，我们利用纳米级相敏结技术在Dirac半金属Bi _{1- x} Sb _x中诱导超导。然后，我们的射频辐射实验揭示了Nb–Bi _0.97 Sb _0.03中4π周期的Andreev束缚态对超电流的重要贡献。–Nb约瑟夫森路口。由于狄拉克锥的非常宽的传输共振和比准粒子中毒速率快的测量频率，因此对超电流有实质4π贡献的条件是有利的。此外，我们表明，在结平面上施加的磁场允许从0到π态调整约瑟夫森结。我们的结果为利用Dirac半金属的拓扑本体性质进行拓扑超导研究和拓扑量子计算机开发开辟了技术上有吸引力的途径。