超流体$^3$He中的拓扑节线与Anderson定理
Topological nodal line in superfluid $^3$He and the Anderson theorem
AI总结：
该研究通过测量超流体$^3$He极性相的能隙温度依赖性，实验验证了杂质散射仅在满足Anderson定理的子系统内混合态时非常规体系具鲁棒性的猜想，为拓扑超导抗无序保护等研究提供支撑。
摘要：
具有各向异性配对的超导与超流——例如铜氧化物中的$d$波与超流体$^3$He中的$p$波——会被杂质强烈抑制。同时，在应用层面，库珀对（Cooper pair）对无序的鲁棒性是人们高度期待的特性。近期有研究提出，若杂质散射仅在满足Anderson定理（该定理可保护常规超导）的各独立子系统内混合准粒子态，那么非常规体系将具备鲁棒性。本文通过测量超流体$^3$He极性相的能隙温度依赖性，对这一猜想进行了实验验证。研究表明，取向一致的柱状非磁性缺陷基本不会改变具有Dirac节线的能谱。尽管散射作用很强，但它保留了沿柱体长度方向的动量，并按照该猜想形成了鲁棒的子系统。这一发现或能推动未来关于拓扑超导抗无序保护机制、以及拓扑费米平带本质的相关实验研究。
英文摘要：
Superconductivity and superfluidity with anisotropic pairing -- such as $d$-wave in cuprates and $p$-wave in superfluid $^3$He -- are strongly suppressed by impurities. Meanwhile, for applications, the robustness of Cooper pairs to disorder is highly desired. Recently, it has been suggested that unconventional systems become robust if the impurity scattering mixes quasiparticle states only within individual subsystems obeying the Anderson theorem that protects conventional superconductivity. Here, we experimentally verify this conjecture by measuring the temperature dependence of the energy gap in the polar phase of superfluid $^3$He. We show that oriented columnar non-magnetic defects do not essentially modify the energy spectrum, which has a Dirac nodal line. Although the scattering is strong, it preserves the momentum along the length of the columns and forms robust subsystems according to the conjecture. This finding may stimulate future experiments on the protection of topological superconductivity against disorder and on the nature of topological fermionic flat bands.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
