Symmetry-protected electron states in ring-like quantum dots

The purpose of this research proposal is to investigate predictions on significantly enhanced lifetimes of electron states in nanostructures with rotational symmetry and engineered spin-orbit interaction.

Finding such new mechanisms to improve coherence of quantum states is important to reduce the need for error correction in applications.

Our research is based on recently developed ring-like quantum dots (QDs), where a rotational symmetry fully suppresses orbital interactions.

We obtain the structures by epitaxial growth of semiconductor nanowires, where atomically flat, disk-shaped QDs form through controlled changes in the crystal structure.Quantum rings have been studied theoretically in great detail, but are difficult to realize experimentally.

A first goal is therefore to understand what makes this system different from those previously studied, such that systematic control of rotational symmetry in mesoscopic semiconductors can be gained.

A second goal is to control intrinsic and extrinsic sources of spin-orbit interaction via engineering of electric fields and the QD crystal structure.

Finally, we will incorporate nearby sensor QDs, and employ spin- and orbital-filtering measurements to probe lifetime of states.The proposed four-year project will primarily involve electron transport studies of the QD properties at low temperature, and will receive support on semiconductor epitaxial growth, microscopy and electron transport theory through existing collaborations.