Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling

TL;DR

This paper demonstrates how the phase of valley-orbit coupling in silicon quantum dots can be manipulated using electric fields to enable controlled rotations of valley states, advancing quantum control techniques.

Contribution

It provides a detailed analytical framework showing how electric fields influence valley phase and enable controllable valley state rotations in silicon quantum dots.

Findings

Electric fields affect the phase of valley-orbit coupling.

Interdot tunneling is enabled by phase differences.

Controlled valley rotations are possible at level anticrossings.

Abstract

A gate electric field has a small but non-negligible effect on the phase of the valley-orbit coupling in Si quantum dots. Finite interdot tunneling between valley eigenstates in a double quantum dot is enabled by a small difference in the phase of the valley-orbit coupling between the two dots, and it in turn allows controllable rotations of two-dot valley eigenstates at a level anticrossing. We present a comprehensive analytical discussion of this process, with estimates for realistic structures.