Bidirectional Single-Electron Counting and the Fluctuation Theorem

TL;DR

This paper combines theoretical and experimental analysis of single-electron tunneling in a quantum dot system, revealing how measurement back-action influences fluctuation theorem validity.

Contribution

It demonstrates the impact of electrometer back-action on tunneling statistics and the fluctuation theorem in quantum dot systems, providing a quantitative correction method.

Findings

Electrometer back-action induces nonequilibrium noise and modifies tunneling statistics.

Fluctuation theorem appears violated without considering back-action.

Accounting for back-action restores the validity of the fluctuation theorem.

Abstract

We investigate theoretically and experimentally the full counting statistics of bidirectional single-electron tunneling through a double quantum dot in a GaAs/GaAlAs heterostructure and compare with predictions of the fluctuation theorem (FT) for Markovian stochastic processes. We observe that the quantum point contact electrometer used to study the transport induces nonequilibrium shot noise and dot-level fluctuations and strongly modifies the tunneling statistics. As a result, the FT appears to be violated. We show that it is satisfied if the back-action of the electrometer is taken into account, and we provide a quantitative estimate of this effect.