Detection of a charged two-level system by using the Kondo and the Fano-Kondo effects in quantum dots

TL;DR

This paper theoretically explores how the Kondo and Fano-Kondo effects in quantum dots can be used to detect the state of a qubit by observing shifts in conductance features, enabling qubit state estimation.

Contribution

It introduces a method to detect qubit states through conductance modulation in quantum dots influenced by Kondo phenomena, providing a new approach for quantum measurement.

Findings

Conductance peaks and dips shift with qubit energy levels

Optimal qubit detection points are identified via conductance shifts

The method allows estimation of qubit tunneling coupling

Abstract

The Kondo effect and the Fano-Kondo effect are important phenomena that have been observed in quantum dots (QDs). We theoretically investigate the transport properties of a coupled QD system in order to study the possibility of detecting a qubit state from the modulation of the conductance peak in the Kondo effect and the dip in the Fano-Kondo effect. We show that the peak and dip of the conductance are both shifted depending on the energy-level of the qubit. In particular, we find that we can estimate the optimal point and tunneling coupling between the |0> and |1> states of the qubit by measuring the shift of the positions of the conductance peak and dip, as functions of the applied gate voltage on the qubit and the distance between the qubit and the detector.