  We report our study of the real-time charge counting statistics measured by a
quantum point contact (QPC) coupled to a single quantum dot (QD) under
different back-action strength. By tuning the QD-QPC coupling or QPC bias, we
controlled the QPC back-action which drives the QD electrons out of thermal
equilibrium. The random telegraph signal (RTS) statistics showed strong and
tunable non-thermal-equilibrium saturation effect, which can be quantitatively
characterized as a back-action induced tunneling out rate. We found that the
QD-QPC coupling and QPC bias voltage played different roles on the back-action
strength and cut-off energy.
