Allan-Deviation Measurements of Gate-Tunable Single Electron Pumps with the Ultrastable Low-Noise Current Amplifier

We characterized KRISS precision measurement system by measuring the Allan deviation of the quantized current generated by GaAs/AIGaAs gate-tunable electron pumps, where the current was amplified by the ultrastable low-nose current amplifier (ULCA) developed by the PTB. The Allan deviation of a phosphor bronze wire generally used at cryogenic temperature showed a white noise level of about 18 fA Hz-1I2. The noise level of the electron pump was improved by a factor 4 with a specific choice of cryogenic cables.