Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 68: Topology: Other Topics

TT 68.9: Vortrag

Freitag, 5. April 2019, 11:45–12:00, H22

Measuring beyond the resolution limit of a detector — •Roman-Pascal Riwar — JARA Institute for Quantum Information (PGI-11), Forschungszentrum Jülich, Germany

We recently made the unexpected prediction that the non-equilibrium transport statistics of conventional sequential electron tunneling are indistinguishable from those of fractional charges -- in the sense that the statistics are effectively equivalent to fractional charges, measured with a detector that can resolve only integer charges. This effect is due to a topological transition of the system-detector dynamics. Here, we consider a potential application of this effect, when we turn it on its head: if we indeed expect to have a detector with insufficient resolution, the presence of fractional processes might not be effective, but in fact real. We propose, that this could lead to the intriguing possibility of measuring discrete stochastic processes that are smaller than the resolution limit. We provide a proof of principle at the practical example of charge detectors measuring transport through localized charge islands, where the detectors are too large to resolve individual islands. Finally, we show that the effect is indeed protected, by explicitly taking into account likely sources of perturbations or measurement errors in the setup.