Low Temperature Voltage Divider and Null Detector

This paper describes a low temperature voltage divider and null detector which are designed to accurately bring the low level voltage of the Josephson steps to the 1 V level. The divider uses the series-parallel interchange of resistors. Preliminary tests indicate that the resistors are stable to within one part in 107 and that the ratio is accurate to within one part in 106. The null detector utilizes a superconducting quantum interference magnetometer and is limited only by the Johnson noise in the cooled resistors.