Steps Towards a Capacitance Standard Based on Single-Electron Counting at PTB

A quantum standard for capacitance is realized by charging a capacitor with a well-known number of electrons and measuring the voltage U across the capacitor by means of a Josephson voltage standard (Williams et al., 1992), This experiment yields quantum determination for the capacitance C = Ne/U where N is the number of electrons and e the elementary charge. Currently, PTB is working on the realization of such an experiment using single-electron pumps for transferring electrons one by one to a cryogenic vacuum capacitor. We report on the progress in the development of the different components for this experiment, with emphasis on measurements characterizing the single-electron tunneling (SET) circuit