VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Wednesday 7
Dots and wires

› 15:50 - 16:10 (20min)
Resolution effects on the distribution of current through a resonant level
Yasuhiro Yamada  1, *@  , Imada Masatoshi  1@  
1 : Department of Applied Physics, University of Tokyo
7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 -  Japan
* : Corresponding author

Recently, it has attracted much attention to investigate distribution of current in mesoscopic systems. For instance, the current noise, which is the variance of the distribution, has been extensively studied as well as the average current. In the actual experiment, the distribution is not only determined by the observed system but also by measurement devices. Although the full counting statistics has been used for calculating the distribution, the inevitable issues of the actual devices, such as resolution, has not been fully considered.

In this study, we propose the quantum two-point measurement with finite resolution. Note that our method is equivalent to the full counting statistics in an ideal condition. Using this method, we analyze resolution effects on the distribution of current flowing the resonant level coupled to two reservoirs. In the unbiased measurement case, it is found that the measured noise becomes a sum of the inherent noise and the excess one. Since the excess noise is always positive, the measured noise is always larger than the inherent noise, which leads to the deviation of the Johnson-Nyquist relation between the measured current and noise at low temperatures.

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