Giant Rabi frequencies between qubit and excited hole states in silicon quantum dots

TL;DR

This paper demonstrates that in silicon quantum dots, transitions involving excited hole states can achieve Rabi frequencies vastly larger than those of ground states, with tunability via bias, advancing qubit control techniques.

Contribution

It extends the analysis of electric-field induced transitions to excited doublet states, revealing significantly larger Rabi frequencies and their dependence on symmetry and bias in silicon quantum dots.

Findings

Excited doublet states exhibit Rabi frequencies several orders higher than ground states.

Rabi frequencies can be widely tuned by adjusting the applied bias.

Symmetry of eigenstates influences transition strengths and frequencies.

Abstract

Holes in Si quantum dots are being investigated for the implementation of electrically addressable spin qubits. In this perspective, the attention has been focused on the electric-field induced transitions between the eigenstates belonging to the ground doublet. Here we theoretically extend the analysis to the first excited doublet. We show that - in a prototypical quantum dot structure - transitions involving the lowest excited states display Rabi frequencies that are several orders of magnitude larger than those occurring in the ground doublet. A clear relation with the symmetries of the eigenstates emerges, as well as a wide tunability of the Rabi frequencies by means of the applied bias. A preliminary discussion on the possible implications of the present results for multilevel manipulation schemes and for multi-hole qubit encodings is provided.