Density of States of Narrow Superconducting Channels in the Regime of Quantum Fluctuations of the Order Parameter
The current–voltage characteristics of superconductor–insulator–semiconductor (S1–I–S2)
tunnel junctions, where superconducting electrode S2 is a thin nanowire, are studied experimentally. The
observed blurring of the gap singularities is interpreted as a manifestation of the order parameter quantum
fluctuations. We propose a model taking into account the broadening of the density of states due to the interaction
of electrons with the Mooij–Schön plasmon mode emerging in a quasi-one-dimensional superconducting
channel in the regime of quantum fluctuations of the order parameter. The model gives results that
are in a reasonable qualitative agreement with the experimental data.