We present a low-temperature experimental test of the fluctuation theorem for electron transport through a double quantum dot. The rare entropy-consuming system trajectories are detected in the form of single charges flowing against the source-drain bias by using time-resolved charge detection with a quantum point contact. We find that these trajectories appear with a frequency that agrees with the theoretical predictions even under strong nonequilibrium conditions, when the finite bandwidth of the charge detection is taken into account.
@article{arxiv.1107.4240,
title = {Irreversibility on the Level of Single-Electron Tunneling},
author = {B. Küng and C. Rössler and M. Beck and M. Marthaler and D. S. Golubev and Y. Utsumi and T. Ihn and K. Ensslin},
journal= {arXiv preprint arXiv:1107.4240},
year = {2012}
}