Electromechanical Manipulation of Transition Metal Dichalcogenides for Quantum Information Applications

Abstract

Two-dimensional semiconductors, particularly transition metal dichalcogenides (TMDs), have garnered significant attention in recent years due to their strong light–matter interactions and unique quantum properties, making them promising candidates for quantum information science. These properties are highly tunable using external electric and strain fields. In this thesis, we explore both static and dynamic approaches to tuning TMDs with these fields to develop quantum information devices. In Chapter 1, we introduce the fundamental properties of TMDs and the mechanisms by which electric and strain fields modulate their behavior. We also review prior work in this area and lay the groundwork for our experiments by introducing surface acoustic waves (SAWs) as a method for dynamic field control. Chapter 2 presents our work demonstrating long-range, directional transport of interlayer excitons in bilayer WSe2 using SAWs. The excitons' intrinsic out-of-plane dipole moment allows them to be trapped in the dynamic potential wells created by the SAW electric field and carried along the propagation direction. We examine this transport across varying SAW powers and temperatures, and introduce an ITO capping layer that suppresses in-plane electric fields to prevent exciton dissociation. In Chapter 3, we investigate quantum emitters in bilayer WSe2 and demonstrate energy tunability via out-of-plane electric fields applied through graphite gates, addressing the challenge of inhomogeneous emission energies. We also report the discovery of phonon sidebands arising from coupling between individual excitons and localized interlayer breathing mode phonons. We quantify this exciton–phonon coupling and explore its tunability with electric field, highlighting opportunities for encoding our quantum emitters with fundamental information from the 2D phonon modes. Chapter 4 details our ongoing work using SAW resonators to dynamically manipulate excitonic states in bilayer WSe2. This platform enables spatial modulation of excitonic properties through standing SAW fields and time-averaged tuning of exciton energies and linewidths. We also investigate the possibility of exciton trapping at SAW anti-nodes and discuss its potential for enhancing exciton–exciton interactions, which could open a path toward excitonic quantum simulations. Finally, in Chapter 5, we synthesize the key results of each project, reflect on their implications, and outline future research directions that build on the integration of dynamic and static control in 2D material systems for scalable quantum technologies.}