The twin radio frequency single electron transistor for correlated charge detection on microsecond time-scales

Towards the ultimate goal of reading out a solid state quantum computer, we have developed a twin radio frequency single electron transistor (rf-SET) device that is capable of cross-correlated measurements of sub-electron charges on microsecond time-scales. The twin rf-SET measurement setup makes use of two tuned resonance circuits to simultaneously and independently address both rf-SETs using wavelength division multiplexing (WDM) and a single cryogenic amplifier. In this work we describe the operation of the twin rf-SET and evaluate the cross-talk between each resonance circuit. The cross-correlation technique is demonstrated using two rf-SETs and is shown to suppress spurious charge noise in real time. For the case of simultaneous operation, the rf-SETs had charge sensitivities of 4.4 mue/root({Hz}) over bar and 7.5 mue/root({Hz}) over bar. (C) 2003 Elsevier Science B.V. All rights reserved.