Feedback Control Of Noise In Transport Through Coupled Quantum Dots

Quantum transport plays a crucial role in the realization of quantum devices.However,carriers are inevitably subjected to various influences in the process of transport,posing a significant challenge to the quantum devices.Among them,shot noise caused by the quantization of carrier charges in non-equilibrium transport results in fluctuations in the number of electrons passing through the quantum device around an average value in unit time.However,shot noise is extremely difficult to control in quantum devices due to charge quantization.Therefore,achieving a controllable low-noise current is essential for high-precision measurements in quantum transport and quantum metrology.Currently,scientists have conducted in-depth research on noise suppression in tunnel junctions or single quantum dot transport devices and successfully suppressed the transport noise of single quantum dots in experiments through feedback control.Compared with single quantum dots,coupled quantum dots have inherent coherence and are the basic units of quantum devices.Therefore,achieving stable low-noise current in coupled quantum dot transport devices is one of the key technologies in quantum device development.This paper systematically studies the noise control of coupled double quantum dot transport systems through a closed-loop feedback control scheme.First,we develop an auxiliary density matrix approach to describe the quantum transport characteristics under feedback.This method is applicable to any transport parameters and can calculate any high-order transport cumulant under feedback control.Secondly,the transport feedback effects under various tunnel coupling parameters are systematically studied.It is found that feedback control of tunneling coupling between the two quantum dots is the most effective feedback scheme.Furthermore,the effects of Coulomb interaction between quantum dots and measurement-induced decoherence on feedback are analyzed.Finally,the transport feedback control with finite time delay is studied in a systematic way.An outlook for future work is also provided.