# Spin-Degenerate Regimes for Single Quantum Dots in Transition Metal Dichalcogenide Monolayers

## TL;DR

This paper investigates conditions under which single quantum dots in transition metal dichalcogenide monolayers can exhibit spin degeneracy despite strong spin-orbit coupling, enabling potential spin qubit applications.

## Contribution

It identifies specific regimes in MoS₂ where spin degeneracy can be achieved by tuning quantum dot parameters, overcoming typical spin-orbit limitations.

## Key findings

- Spin degeneracy regimes are achievable in MoS₂ quantum dots.
- Degeneracy occurs at specific dot radii and magnetic fields.
- Potential for spin qubits in TMDC monolayers is demonstrated.

## Abstract

Strong spin-orbit coupling in transition metal dichalcogenide (TMDC) monolayers results in spin resolvable band structures about the $K$ and $K'$ valleys such that the eigenbasis of a 2D quantum dot (QD) in a TMDC monolayer in zero field is described by the Kramers pairs $|0\rangle_-=|K'\uparrow\rangle$, $|1\rangle_-=|K\downarrow\rangle$ and $|0\rangle_+=|K\uparrow\rangle$, $|1\rangle_+=|K'\downarrow\rangle$. The strong spin-orbit coupling limits the usefulness of single TMDC QDs as spin qubits. Possible regimes of spin-degenerate states, overcoming the spin-orbit coupling in monolayer TMDC QDs are investigated in both zero field, where the spin and valley degrees of freedom become fourfold degenerate, and twofold degeneracy in some magnetic field, localised to a given valley. Such regimes are shown to be achievable in MoS$_{2}$, where the spin orbit coupling is sufficiently low and of the right sign such that the spin resolved conduction bands intersect at points about the $K$ and $K'$ valleys and as such may be exploited by selecting suitable critical dot radii.