Bogoliubov quasiparticles play a crucial role in understanding the behavior of a superconductor and in achieving reliable operations of superconducting quantum circuits. Diagnosis of quasiparticle poisoning at the nanoscale provides invaluable benefits in designing superconducting qubits. Here, we use scanning tunneling noise microscopy to locally quantify quasiparticles by measuring the effective charge. Using the vortex lattice as a model system, we directly visualize the spatial variation of the quasiparticle concentration around superconducting vortices, which can be described within the Ginzburg–Landau framework. This shows a direct, noninvasive approach for the atomic-scale detection of relative quasiparticle concentration as small as 10−4 in various superconducting qubit systems. Our results alert of a quick increase in quasiparticle concentration with decreasing intervortex distance in vortex-based Majorana qubits.

中文翻译：

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直接可视化超导涡流周围的准粒子浓度


Bogoliubov 准粒子在理解超导体的行为和实现超导量子电路的可靠操作方面起着至关重要的作用。纳米级准粒子中毒的诊断为设计超导量子比特提供了宝贵的好处。在这里，我们使用扫描隧道噪声显微镜通过测量有效电荷来局部量化准粒子。使用涡旋晶格作为模型系统，我们直接可视化了超导涡旋周围准粒子浓度的空间变化，这可以在 Ginzburg-Landau 框架中进行描述。这显示了一种直接、无创的方法，用于在各种超导量子比特系统中对小至 10-4 的相对准粒子浓度进行原子级检测。我们的结果提醒说，在基于涡旋的 Majorana 量子比特中，准粒子浓度随着涡旋间距离的减小而迅速增加。