The single electron R-pump: first experiment
  We fabricated and tested the single electron R-pump, i.e. a three-junction Al circuit with on-chip Cr resistors. We show that due to the presence of the resistors (R > h/e^2 = 25.8 kOhm), the accuracy of electron transfer in the R-pump can approach the level of 10^-8. Preliminary results of experiment with the R-pump made at PTB are reported. 
S. V. Lotkhov, S. A. Bogoslovsky, A. B. Zorin and J. Niemeyer