Adiabatic Transfer of Electrons in Coupled Quantum Dots

TL;DR

This paper explores how dissipation affects electron transfer and quantum gate operations in coupled quantum dots, providing analytical tools to quantify fidelity loss and proposing methods to visualize quantum coherence.

Contribution

It introduces a formalism to analyze dissipation effects on adiabatic electron transfer and two-qubit operations in quantum dots, including fidelity loss calculations.

Findings

Fidelity loss during adiabatic electron transfer is quantified.

Charge tunneling impacts two-qubit gate fidelity.

Potential to visualize quantum oscillations in electron pump currents.

Abstract

We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo) spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the `fidelity loss' during a simple operation that adiabatically moves an electron between two coupled dots. We discuss the possibility of visualizing coherent quantum oscillations in electron `pump' currents, combining quantum adiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the role of intermediate charge states has been discussed recently, we apply our formalism to calculate the fidelity loss due to charge tunneling between two dots.