An improved Josephson potentiometer system for the measurement of the quantum Hall effect

Several improvements have been made on a Josephson potentiometer and superconducting quantum interference device (SQUID) galvanometer system previously reported. Results of the measurement of the quantized Hall resistance obtained by the use of this system are in agreement with those obtained by means of a conventional potentiometer system to 0.02 ± 0.08 ppm for silicon-MOSFET samples. A comparison of the Hall resistance between two different quantized values corresponding to h/4e
²
and h/8e
²
, for a sample, has been made without an uncertainty associated with the linearity of voltage-ratio measurements. A discussion is presented in relation to completeness of the quantization.