MULTITERMINAL COUNTING STATISTICS

摘要

We have reviewed here a constructive theory of counting statistics for electron transfer in multi-terminal mesoscopic systems. We have covered two opposite limit of weak and strong interaction. For the case of weakly interacting electrons, when the conductance of the system G G_Q, the theory of FCS reduces to a circuit theory of 2 x 2 matrices associated with Keldysh Green functions. In the Coulomb blockade limit, G G_Q, the FCS methods turns out to be an extension of the usual master equation approach. We have applied these methods to study the FCS of charge transfer through the three-terminal quantum dot. Surprisingly, the FCS has a similar qualitative features both in weakly and strongly interacting regimes. We found that Coulomb interaction suppresses the relative probabilities of big current fluctuations in the dot. We have also reviewed the scattering approach to FCS in multi-terminal circuits. Then by considering the generic model of a single resonance level, we have established the equivalence of scattering and master equation approaches to FCS. The theories presented enables one for easy theoretical prediction of the FCS for a given practical layout. Thereby they facilitate experimental activities in this direction. Up to now, only the noise has been measured. In our opinion, the measurements of FCS can be easily performed with threshold detectors that produce a signal provided the current in a certain terminal exceeds the threshold value. If the threshold value exceeds the average current, the detector will be switched by this relatively improbable fluctuation of the current. The signal rate will be thus proportional to the probability of these fluctuations P(I), the value given by the theory of FCS.