Grad Talk- 2D Materials and Single Quantum Emitters (SQEs)

Abstract: (Two-dimensional (2D) materials have been shown to exhibit novel solid-state physics and applications in nanotechnology. 2D materials are atomically thin crystals composed of a single layer of atoms or molecules. These materials exhibit electronic, magnetic, and optimal phenomena which depends on the number of layers. They also offer the ability to “stack” distinct layers of materials on top of one another to create van der Waals heterostructures, which change the properties of the material as well as the corresponding light-matter interactions. Through this presentation I will provide a brief introduction to 2D materials and discuss my work on single quantum emitters (SQEs) in transition metal dichalcogenides (TMDs). TMDs are a class of 2D semiconductors which possess a direct band gap when it is a monolayer. They are distinct from other semiconductors due to the valley-structure and spin-valley coupling within its band structure. TMDs have recently been found to host SQEs attributed to confining potentials which trap single excitons. The photons emitted by SQEs are 50-100 meV below the neutral excitonic resonance and have linewidths of around 130 μeV. My long term plan is to develop devices designed to trap single electrons in these confining potentials to serve as a long-lived spin-qubit for quantum information applications. However, these SQEs are known to undergo spectral fluctuations due to localized charge fluctuation effects from substrates which are often doped. I am developing heterostructures to reduce these spectral fluctuations as well as to control the SQE emission through charge doping. The heterostructure consists of hBN-encapsulated WSe2 with graphene on both sides to gate the WSe2 and provide a charge source. In my measurements I have shown quantum control of excitons. 
 
** Refreshments served from 2:45pm – 3:00pm in PAS 218. Please join us for the colloquium in PAS 224. Thank you. **