Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 21: Transport: Fluctuations and Noise

TT 21.4: Talk

Tuesday, March 24, 2009, 15:15–15:30, HSZ 304

Tunable dynamical channel blockade in double-dot Aharonov-Bohm interferometers — •Daniel Urban and Jürgen König — Unversität Duisburg-Essen and CeNIDE

We study electronic transport through an Aharonov-Bohm interferometer with single-level quantum dots embedded in the two arms. The full counting statistics in the shot-noise regime is calculated to first order in the tunnel-coupling strength. The interplay of interference and charging energy in the dots leads to a dynamical channel blockade, resulting in enhanced cumulants. This effect is tunable by the magnetic flux penetrating the Aharonov-Bohm ring.

The origin of the blockade lies in the decoupling of the double dot's Hilbert space into two subspaces, one containing the singlet and one containing the three triplet states: Consequent filling of an empty dot with two electrons from the source results in the singlet state, i.e. the triplet can only be reached by tunneling out to the drain. Since the subspaces differ in their transport properties, this leads to super-Poissonian noise. When the flux assumes integer multiples of the flux quantum, tunneling out is suppressed, so that the subspaces decouple and the second and higher cumulants diverge.

[1] D. Urban and J. König, arXiv:0811.4723