A superconductor subject to electromagnetic irradiation in the terahertz range can show amplitude oscillations of its order parameter. However, coupling this so-called Higgs mode to the charge current is notoriously difficult. We propose to achieve such a coupling in a particle-hole-asymmetric configuration using a DC-voltage-biased normal-metal–superconductor tunnel junction. Using the quasiclassical Green's function formalism, we demonstrate three characteristic signatures of the Higgs mode: (i) The AC charge current exhibits a pronounced resonant behavior and is maximal when the radiation frequency coincides with the order parameter. (ii) The AC charge current amplitude exhibits a characteristic nonmonotonic behavior with increasing voltage bias. (iii) At resonance for large voltage bias, the AC current vanishes inversely proportional to the bias. These signatures provide an electric detection scheme for the Higgs mode.

中文翻译：

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希格斯模式在通过普通金属-超导体结传输中的特征

在太赫兹范围内受到电磁辐射的超导体可以显示其阶跃参数的振幅振荡。然而，将这种所谓的希格斯模式耦合到充电电流是非常困难的。我们建议使用直流电压偏置的正态金属-超导体隧道结，以粒子-孔非对称结构实现这种耦合。使用准古典格林函数形式论，我们证明了希格斯模式的三个特征性特征：（i）交流充电电流表现出明显的共振行为，并且在辐射频率与阶次参数一致时达到最大值。（ii）随着电压偏置的增加，交流充电电流幅度呈现出非单调的特征。（iii）在谐振时产生较大的电压偏置，AC电流与偏置成反比地消失。这些签名为希格斯模式提供了一种电检测方案。