  In superconductors (SC), the Higgs amplitude mode is a coherent oscillation
of the order parameter typically generated by THz laser irradiation. In this
paper we propose to probe the Higgs mode using electronic transport in
ballistic superconducting hybrid devices. We first confirm the existence of a
non-zero amplitude mode in the clean case using the Keldysh-Eilenberger
formalism. We then investigate two different geometries, respectively a
normal-insulating-superconductor (NIS) tunnel junction and a NSN junction with
transparent interfaces, the superconductor being irradiated in both situations.
In the NIS case, the Higgs manifests itself in the second-order AC current
response which is resonant at the Higgs frequency. In the NSN case, the DC
differential conductance allows to probe the gaps generated by the Higgs mode
in the Floquet spectrum.
