Metrology triangle using a Watt balance, a calculable capacitor and a single-electron tunnelling device

The combination of a Watt balance, a calculable capacitor and a single-electron tunnelling device forms a triangle that yields a value for the single-electron charge quantum Q(S) in terms of the SI coulomb. Importantly, this result is independent of the Josephson and quantum Hall effects, and thus avoids the possible confounding corrections from these two effects that arise in the traditional quantum metrology triangle. This new triangle can be used to test for corrections to the expected relation Q(S) = e, where e is the elementary charge. Combining existing results for Watt balances, calculable capacitors and an electron counting capacitance standard yields (Q(S)/e) - 1 = (-0.09 +/- 0.92) x 10(-6).