We address the measurement of density of states within and beyond thesuperconducting gap in tunnel-coupled finite-size nanostructures using acapacitive method. Third-harmonic generation is used to yield the fulldifferential conductance spectrum without destruction of the low dimensionalityotherwise induced by intimate ohmic coupling to an electrode. The method isparticularly relevant to attempts to discern the presence of the fragileMajorana quasiparticle at the end of spin-orbit-coupled nanowires inappropriate magnetic field conditions by their signature mid-gap density ofstates.
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