noise in coupled dots and the “ fractional charges ”

We consider the problem of shot noise in resonant tunneling through double quantum dots in the case of interacting particles. Using a many-body quantum mechanical description we evaluate the energy dependent transmission probability, the total average current and the shot noise spectrum. Our results show that the obtained reduction of the noise spectrum, due to Coulomb interaction, can be interpret in terms of non–interacting particles with fractional charge like behavior. The notion of quasi–particles of fractional charge has been introduced for almost two decades to explain the Fractional Quantum Hall (FQH) effect [1]. Yet, despite intensive efforts, the nature of these quasi–particles is not completely understood. An important progress, however, has been made in this direction with experiments on quantum shot-noise [2–4] leading to direct measurement of the quasi–particle fractional charge. In fact, for non-interacting particles of charge q the zero frequency spectral density at zero temperature is given by [5] S(0) = 2qI(1 − t) , (1) where I is the current and t is the transmission coefficient through the device. In the FQH regime q is given by the quasi–particle charge, e * .