Long hold times in a two-junction electron trap

Authors :: Kemppinen, A.
Lotkhov, S. V.
Saira, O. -P.
Zorin, A. B.
Pekola, J. P.
Manninen, A. J.
Publication Year :: 2011
Abstract: The hold time $\tau$ of a single-electron trap is shown to increase significantly due to suppression of environmentally assisted tunneling events. Using two rf-tight radiation shields instead of a single one, we demonstrate increase of $\tau$ by a factor exceeding $10^3$, up to about 10 hours, for a trap with only two superconductor (S) -- normal-metal (N) tunnel junctions and an on-chip resistor $R$ (R-SNS structure). In the normal state, the improved shielding made it possible to observe $\tau\sim$ 100 s, which is in reasonable agreement with the quantum-leakage-limited level expected for the two-electron cotunneling process.<br />Comment: 4 pages, 3 figures