Charge sensitivity of the inductive single-electron transistor

Abstract

We calculate the charge sensitivity of a recently demonstrated device where the Josephson inductance of a single Cooper-pair transistor is measured. We find that the intrinsic limit to detector performance is set by oscillatorquantum noise. Sensitivity better than 10−6e/√Hz is possible with a high Q value ∼103, or using a superconducting quantum interference deviceamplifier. The model is compared to experiment, where charge sensitivity 3×10−5e/√Hz and bandwidth 100 MHz are achieved.