**Lucas Maisel and Rosa López \***

Institut de Física Interdisciplinària i de Sistemes Complexos IFISC (CSIC-UIB), E-07122 Palma de Mallorca, Spain; lucas.maisel@gmail.com

**\*** Correspondence: rosa.lopez-gonzalo@uib.es

Received: 24 October 2019; Accepted: 11 December 2019; Published: 19 December 2019

**Abstract:** In the present work, we study a mesoscopic system consisting of a double quantum dot in which both quantum dots or artificial atoms are electrostatically coupled. Each dot is additionally tunnel coupled to two electronic reservoirs and driven far from equilibrium by external voltage differences. Our objective is to find configurations of these biases such that the current through one of the dots vanishes. In this situation, the validity of the fluctuation–dissipation theorem and Onsager's reciprocity relations has been established. In our analysis, we employ a master equation formalism for a minimum model of four charge states, and limit ourselves to the sequential tunneling regime. We numerically study those configurations far from equilibrium for which we obtain a stalling current. In this scenario, we explicitly verify the fluctuation–dissipation theorem, as well as Onsager's reciprocity relations, which are originally formulated for systems in which quantum transport takes place in the linear regime.

**Keywords:** quantum transport; quantum dots; fluctuation–dissipation theorem; Onsager relations
