Time-correlated single-electron tunneling in one-dimensional arrays of ultrasmall tunnel junctions

We have obtained convincing experimental evidence of the time correlation of single-electron tunneling (SET) events, i.e., of SET oscillations with the average frequency fₛ fundamentally related as fₛ=I/e to the dc current I. The experiments have been carried out with one-dimensional N-junction arrays of Al/oxide/Al tunnel junctions of area S{}0.006 {μ}m² at T{}60 mK. The correlation showed up as resonance peaks of the dynamic resistance dV/dI as a function of I, arising at I=Iₙ=nef (n=±{}1 and ±{}2) at irradiation of the N=15 and 19 samples by microwaves of frequency f=0.7--5 GHz.