CRYOGENIC PRECISION CAPACITANCE BRIDGE USING A SINGLE-ELECTRON TUNNELING ELECTROMETER

The electronic charge can be determined by placing a known number of e lectrons on a calibrated capacitor and measuring the resulting voltage . Single electron tunneling (SET) electrometers with sufficient sensit ivity for this application have been fabricated. We report on the desi gn and preliminary results of a capacitance bridge experiment using an SET electrometer to measure two capacitors in a dilution refrigerator . This includes discussion of issues such as the leakage rate of a cap acitor at cryogenic temperatures and the optimum coupling of the elect rometer to the bridge circuit.