SINGLE COOPER PAIR ELECTROMETER BASED ON A RADIO-FREQUENCY-SQUID SCHEME

摘要

A superconducting electrometer is described which is based on charge modulation of the Josephson supercurrent circulating in a superconducting loop including the Cooper pair transistor. This current is radio-frequency-driven by means of a high-Q resonance tank circuit inductively coupled to the loop. The variations of the polarization charge on the transistor island (input signal) are converted into variations of amplitude and phase of steady oscillations inside the tank. These oscillations are amplified and then detected. The noise characteristics and the advantages of this electrometer for the readout of the charge-qubit state are discussed.