Effective theory of monolayer TMDC double quantum dots

Alessandro David,Guido Burkard,Andor Kormányos

doi:10.1088/2053-1583/aac17f

Abstract

Monolayer transition metal dichalcogenides (TMDCs) are promising candidates for quantum technologies, such as spin qubits in quantum dots, because they are truly two-dimensional semiconductors with a direct band gap. In this work, we analyse theoretically the behaviour of a double quantum dot (DQD) system created in the conduction band of these materials, with two electrons in the (1,1) charge configuration. Motivated by recent experimental progress, we consider several scenarios, including different spin–orbit splittings in the two dots and including the case when the valley degeneracy is lifted due to an insulating ferromagnetic substrate. Finally, we discuss in which cases it is possible to reduce the low energy subspace to the lowest Kramers pairs. We find that in this case the low energy model is formally identical to the Heisenberg exchange Hamiltonian, indicating that such Kramers pairs may serve as qubit implementations.

Highlights

Monolayers of transition metal dichalcogenides (TMDCs) are a class of 2D materials with very interesting electronic and optical properties [1, 2]
Theoretical investigation of quantum dots (QDs) in TMDCs started with QDs in gated nanoribbons [27] and the magnetic field dependence of the single-electron spectrum [7] and it includes studies of valley hybridisation [28], flake QDs of triangular and hexagonal shape and nanoribbons [29, 30], the valley Zeeman effect [31], optical control of a spin-valley qubit [32], spin-degenerate regimes for small QDs in a magnetic field [33], spin relaxation [34], electric control of a spin-valley qubit [35] and a model of valley qubit [36]
Assuming equation (9) and 2∆ > J we see from figure 2(c) that the subspace spanned by the states of N × N is the low energy subspace (LES), where, N × N = |K ↓; K ↓, |K ↓; K ↑

Summary

Introduction

Monolayers of transition metal dichalcogenides (TMDCs) are a class of 2D materials with very interesting electronic and optical properties [1, 2]. Assuming equation (9) and 2∆ > J (which is usually the case for TMDCs at low detuning) we see from figure 2(c) that the subspace spanned by the states of N × N ( called N × N -sector) is the LES, where, N × N = |K ↓; K ↓ , |K ↓; K ↑ ,

Results

Conclusion