Back-action-induced non-equilibrium effect in electron charge counting statistics

We study real-time charge-counting statistics measured by a quantum point contact (QPC) coupled to a single quantum dot (QD) subject to different back-action strengths. By tuning the QD-QPC coupling or the QPC bias, we control the QPC back-action, which drives the QD electrons out of thermal equilibrium. The random telegraph signal (RTS) statistics show strong and tunable non-thermal-equilibrium saturation effect, which can be quantitatively characterized as a back-action-induced tunneling-out rate. We find that the QD-QPC coupling and QPC bias voltage play different roles in determining the back-action strength and the cut-off energy. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3691255]