Double-island single-electron transistor for noise-suppressed detection of charge transfer

In order to access the computational result stored in a quantum computer, the state of a quantum-bit (qubit) needs to be read out. Single-electron transistors (SETs) have been shown to meet the requirements of sensitivity, low back-action, and speed required for quantum-state read-out. Despite these advantages, SETs are susceptible to random charge noise associated with trapping/de-trapping processes in the substrate or tunnel barrier oxide. These random events lead to spurious signals in the SET output and make reliable measurement difficult. In order to overcome this limitation, recent experiments have focused on using two SET detectors to suppress background charge noise by cross-correlating the signals. Here, we report measurements on a double-island SET, which has the potential to suppress the effect of charge noise during readout using only a single device. (C) 2003 Elsevier Science B.V. All rights reserved.