Charge distribution is a basic aspect of electrical transport. In this work we investigate the self-consistent charge response of normal-superconducting heterostructures. Of interest is the variation of the charge density due to voltage changes at contacts and due to changes in the electrostatic potential. We present response functions in terms of functional derivatives of the scattering matrix. We use these results to find the dynamic conductance matrix to lowest order in frequency. We illustrate similarities and differences between normal systems and heterostructures for specific examples such as a ballistic wire and a quantum point contact.

• Received 5 July 2001

DOI:https://doi.org/10.1103/PhysRevB.65.045321