A numerical study of the accuracy of single-electron current standards

We have developed an algorithm for the analysis of single-electron standards of de current. The algorithm is based on numerical solution of the master equation describing the time evolution of the probabilities of the electric charge states of the system, with iterative refinement of the operational set of states. To illustrate the method we have analyzed several standards of de current. We have shown that the accuracy of the single-electron pump may be improved dramatically at lower frequencies and temperatures by replacing the traditional triangular drive wave forms with a special step-like drive. We have also shown that the M-junction turnstile does not achieve the accuracy of the 5-junction pump with the same values of capacitances and resistances even at M=8. However, a hybrid M-junction pump/turnstile system which is easier to control than the 5-junction pump, exhibits a comparable accuracy already at M=6. (C) 1996 American Institute of Physics.