Correlated electron transport through quantum dots - kondo cloud and fractional quantum hall edge

Abstract

We theoretically study many-body effects on electron transport through three different systems consisting of quantum dots; Kondo cloud in a quantum dot, suppression of the interference in a quantum dot with a 2=3 filling fractional quantum Hall edge, and electron pair tunneling in a double-dot interferometry. We propose a setup to directly measure the Kondo screening cloud formed by a quantum dot coupled to semi-infinite quantum wires, on which an electrostatic gate voltage is applied at distance L from the dot. We show that the Kondo cloud, and hence the Kondo temperature and the conductance through dot, is affected by the gate voltage, as L increases below the Kondo cloud length. Based on this behavior, the cloud length can be experimentally identified by changing L with a keyboard type of gate voltages or tuning the coupling strength between dot and the wires. The fractional quantum Hall system with filling factor 2/3 has an edge state composed of counterpropagating chiral charge and neutral modes. We propose an Aharonov-Bohm(AB) interferometry consisting of a large-size quantum dot with a 2/3 filling fractional quantum Hall edge in order to investigate how the neutral mode spoils the AB interference signals and estimate the velocity of neutral mode. The dot is coupled to two leads via electron tunneling. In the sequential tunneling regime, we find that the fractionalization results in the dephasing of AB interference. In addition, in the case of the small velocity of neutral mode compared to charge mode, the AB oscillation with the period of one flux quantum is severely suppressed by a topological effect, and hence the AB oscillation with the period of one half flux quantum dominantly appears. Finally, we propose an Aharonov-Bohm interferometry consisting of two quantum dots for detecting an electron pair tunneling resonance. We find that in the second harmonics of the interference current, pair tunneling processes give a leading nonmonotonous contribution ...