Characterization of a Differential Radio-Frequency Single-Electron   Transistor
  We have fabricated and characterized a new type of electrometer that couples two parallel single-electron transistors (SETs) to a radio-frequency tank circuit for use as a differential RF-SET. We demonstrate operation of this device in summing, differential, and single-SET operation modes, and use it to measure a Coulomb staircase from a differential single Cooper-pair box. In differential mode, the device is sensitive to uncorrelated input signals while screening out correlated ones. 
J.F. Schneiderman, P. Delsing, M.D. Shaw, H.M. Bozler, and P.M.   Echternach