Five and three quantum dot systems as apparatuses for measuring energy-levels

TL;DR

This paper theoretically investigates three and five quantum dot systems as measurement devices for energy levels, analyzing their transport properties and the trade-offs involved in measurement strength and back-action.

Contribution

It introduces a theoretical framework for using side-QD systems as measurement apparatuses for energy levels, focusing on transport properties and optimal coupling strengths.

Findings

Medium coupling strength is optimal for energy-level difference measurement.

Transport properties depend on energy differences of side-QDs.

Back-action effects influence measurement accuracy.

Abstract

A quantum dot (QD) system provides various quantum physics of nanostructures. So far, many types of semiconductor QD structures have been fabricated and investigated experimentally and analyzed theoretically. Presently, QD systems have attracted considerable attention as units for the qubit system of quantum computers. Therefore, it is vital to integrate QD systems as measurement devices in addition to qubits. Here, we theoretically investigate the side-QD system as a measurement apparatus for energy-levels of the target QDs. We formulate the transport properties of both three and five QDs based on the Green functions method. The effects of the energy-difference of two side-QDs on the measurement current are calculated. The trade-off between the strength of the measurement and the back-action induced by the measurement is discussed. It is found that the medium coupling strength is appropriate for reading out the difference of the two energy-levels.