基于量子点接触的开放双量子点系统电子转移特性

The electron transfer properties of an open double quantum dot based on a quantum point contact

基于量子点接触探测器(QPC)理论上研究了双量子点(DQD)系统在耗散环境和纯退相环境影响下的电子转移特性.结果表明,耗散环境中探测器导致的退相干会增大平均电流和Fano factor随时间演化的值,并观察到量子芝诺效应的存在.在对称的DQD情况下,弛豫减小了平均电流随时间演化的震荡振幅.在非对称的DQD情况下,弛豫降低了Fano factor随时间演化的峰值.纯退相环境中测量会阻碍共隧穿过程中不同电流通道之间的转换,导致Fano factor的极高值.在对称的DQD情况下,增大纯退相速率会提高Fano factor.在非对称的DQD情况下,动力学随时间的演化对纯退相环境不敏感.另外,还发现探测器内n个电子的转移几率只受QPC与DQD耦合的影响.我们的结论可以为实验工作者研究电子输运特性提供理论参考.

We theoretically study the electron transfer properties of a double quantum dot system in dissipative and pure dephasing environments based on a quantum dot contact detector.Theoretical results show that in the dissipative environment,the decoherence caused by the detector would increase the stable value of the average current and Fano factor as functions of time.Meanwhile,we find the existence of the quantum Zeno effect during the process of dynamical evolution.In the case of symmetric DQD,the relaxation caused by the dissipative environment would decrease the amplitude of the average current with time evolution and increase the value of the Fano factor in the long time limit.In the case of asymmetric DQD,the relaxation reduces the peak value of Fano factor over time.In the pure dephasing environment,we find that the frequent measurement would hinder the switch between different current channels during the cotunneling process.This results in a high value of Fano factor.In the case of symmetric DQD,increasing the pure dephasing rate would improve the value of Fano factor.In the case of asymmetric DQD,the dynamical evolution with time is not sensitive to the pure dephasing rate.In addition,it is indicated that the transfer probability of electron in the detector is only affected by the coupling between QPC and DQD.The environments have no effect on the transfer of a single electron in the detector.Our theoretical results provide theoretical references for experimental researchers to study the electron transport properties.