Charge States in Andreev Quantum Dots

Abstract

We study the charge states in Andreev quantum dot, the metallic quantum dot coupled to the superconducting ring.We show that breaking the electron-hole symmetry in a superconductor generates non-integer charge, localized in a metallic part of the Andreev quantum dot.We demonstrate that this non-integer charge varies continuously as a result of the electrostatic gating and/or change in the phase difference between the superconducting banks.We investigate charge fluctuations associated with the electron-phonon coupling and Coulomb interactions.We propose a recipe for measuring the charge enabling the design of a sensor for weak magnetic fields whose working element is the Andreev quantum dot.