Signatures of the Higgs mode in transport through a normal-metal–superconductor junction

Gaomin Tang; Wolfgang Belzig; Ulrich Zülicke; Christoph Bruder

doi:10.1103/PhysRevResearch.2.022068

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Signatures of the Higgs mode in transport through a normal-metal–superconductor junction

Gaomin Tang, Wolfgang Belzig, Ulrich Zülicke, Christoph Bruder

DOI 10.1103/PhysRevResearch.2.022068 · Physical Review Research

T1

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Abstract

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.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NbN Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown