The realization of the quantum metrological triangle at the Physikalisch-Technische Bundesanstalt (PTB) is based on calibration capabilities for the capacitance towards a Quantum-Hall resistance, the Josephson voltage standard, and an Electron Counting Capacitance Standard (ECCS) experiment. For transferring electrons one by one onto a cryogenic vacuum capacitor with a decade capacitance of 1 pF a so-called r-pump will be used. All components are presently under investigation before the complete measurement setup will be employed. While the cryogenic capacitance value shows better than 10-6 reproducibility after cycling, the measured dwell times of the electrons of 30 seconds could be too short for closing the triangle with the aimed uncertainty of less than 10-7. Furthermore, calibration capabilities for the capacitance to a calculable capacitor and towards a Quantum-Hall resistance are improved.
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