Constraints on Parallel Operation of Single-Electron Current Sources without Multiplexing

Single-electron sources are promising for developing a standard of the ampere by pumping one electron per cycle at a frequency f, producing a current, I = ef. Presently, these sources produce currents of ~100 pA, and there is an effort to increase this value. While the current increases with f, there is a concomitant, and unacceptable increase in error rates. An alternative to increasing f, which is thought to have a higher likelihood of success, is parallelizing single-electron sources to produce a current I = Nef, where N is the number of parallelized devices. However, variability in operating parameters between devices means it is likely that multiplexing must be incorporated in any resulting standard. Here, to simplify operation as much as possible, we investigate the possibility that some parameters will not need to be multiplexed. To do this, we simulate distributions of device parameters and determine constraints on the variability to achieve minimum current plateau sizes. These simulations clarify the relative importance of improving device uniformity and integrating multiplexers in developing a current standard.