Transport properties of a quantum dot with superconducting leads

TL;DR

This paper presents a numerical study of quantum dot transport with superconducting leads, highlighting temperature effects, photon-assisted tunneling, and potential applications in millimeter wave technology.

Contribution

It introduces a phenomenological model for quantum dot transport with superconducting leads and explores thermal and photon-assisted effects not previously detailed.

Findings

Qualitative agreement with experimental I-V characteristics at low temperatures

Thermal excitation of quasiparticles affects transport at higher temperatures

Photon-assisted tunneling shows potential for millimeter wave applications

Abstract

We report a numerical study of transport properties of a quantum dot with superconducting leads. We introduce a general phenomenological model of quantum dot transport, in which electron tunnel rates are computed within the Fermi's Golden Rule approach. The low temperature current-voltage (I-V) characteristics are in qualitative agreement with experimental observations of Ralph et al. [Phys. Rev. Lett., 74, 3241 (1995)]. At higher temperatures, our results reveal new effects due to the thermal excitation of quasiparticles in the leads as well as the thermal population of excited quantum levels in the dot. We also study the photon-assisted tunneling phenomena in our system and point out its potential for millimeter wave applications.