THERMAL NOISE OF DC JOSEPHSON CURRENT IN A SUPERCONDUCTOR-QUANTUM-DOT-SUPERCONDUCTOR SYSTEM

Abstract

The thermal noise of DC Josephson current in the superconducting leads coupled with a quantum dot system is investigated, and the general thermal current noise formula is derived in the presence of Zeeman field. The resonant structure versus gate voltage and Zeeman energy are displayed. Novel structures associated with the bound state and normal energy state are obtained. As the temperature is low, the Andreev reflection plays an important role in thermal noise and this provides new channels for electron to tunnel. However, if the temperature is high enough, the thermal noise due to Andreev reflection is trivial compared with the normal transport one. The thermal noise versus phase difference is also given to exhibit the temperature dependence. The Fano factor versus phase is much larger than 1 if the temperature is nonzero.