Positive cross-correlations due to Dynamical Channel-Blockade in a three-terminal quantum dot

TL;DR

This paper studies current fluctuations in a three-terminal quantum dot, revealing how dynamical channel-blockade can produce positive cross-correlations and super-Poissonian noise, with implications for quantum transport experiments.

Contribution

It demonstrates the conditions under which dynamical channel-blockade causes positive cross-correlations and super-Poissonian noise in a three-terminal quantum dot system, including effects of spin degeneracy.

Findings

Super-Poissonian Fano factor observed in input current.

Positive cross-correlations between output currents due to dynamical channel-blockade.

Lifting spin degeneracy affects the emergence of these effects.

Abstract

We investigate current fluctuations in a three-terminal quantum dot in the sequential tunneling regime. In the voltage-bias configuration chosen here, the circuit is operated like a beam splitter, i.e. one lead is used as an input and the other two as outputs. In the limit where a double occupancy of the dot is not possible, a super-Poissonian Fano factor of the current in the input lead and positive cross-correlations between the current fluctuations in the two output leads can be obtained, due to dynamical channel-blockade. When a single orbital of the dot transports current, this effect can be obtained by lifting the spin-degeneracy of the circuit with ferromagnetic leads or with a magnetic field. When several orbitals participate in the electronic conduction, lifting spin-degeneracy is not necessary. In all cases, we show that a super-Poissonian Fano factor for the input current is not equivalent to positive cross-correlations between the outputs. We identify the conditions for obtaining these two effects and discuss possible experimental realizations.