Summary
As monolayers, transition metal dichalcogenides (TMDCs) – such as tungsten diselenide (WSe2) – become direct-bandgap semiconductors capable of emitting light. Compared to conventional direct-bandgap semiconductors, such as III-V semiconductors like GaAs, excitons (quasiparticles made of an electron hole bound with an electron) and single-layer TMDCs (SL-TMDCs) have much stronger binding energy. Excitons and SL-TMDCS also have an extra degree of freedom called “k-valley index” or “pseudospin”, which couples with their spin in the presence of light. Due to the way the spin and valley degrees of freedom couple together, excitons in SL-TMDCs can act as a two-level quantum system, whose quantum state can be initialized and controlled with photons of specific polarization, either collectively or as individual excitons confined in quantum dots. To utilize these two-level quantum systems as solid-state qubits in a quantum device, the spectral and temporal dynamics of SL-TMDC excitons in the presence of electric and optical fields needs to be investigated. However, some of the exciton processes in SL-TMDCs happen at timescales that are beyond the resolution of streak cameras used for studies of excitons in conventional semiconductors. To overcome this problem, this research will use femtosecond photoluminescence up-conversion (fsPLupC). This technique relies on sum frequency generation that arises when the photoluminescence signal overlaps with a reference femtosecond (fs) pulse inside a non-linear crystal. It can reveal both temporal and spectral information about the studied processes, potentially with a resolution better than 100 fs. This work will provide a greater fundamental understanding of TMDC monolayers and explore their potential use as ‘valleytronic’ based quantum devices.
Related Content
Silicon Platform for Electron Spin Qubits
Summary Scaling solid-state quantum processors to a useful threshold while maintaining the requisite precision in quantum control remains a challenge. We propose a quantum metal-oxide-semiconductor (QMOS) architecture operating at cryogenic temperatures that is based on a network/node approach as a means to scalability. By working with QMOS, we benefit from the deep investments and […]
December 7, 2018
Portable Quantum Dot Measurement System
Summary Detecting heavy metals in water is essential to ensure clean drinking water and appropriate regulatory decisions following an accident (e.g., a spill) or an emergency. Traditionally, high-sensitivity detection of heavy metals requires bulky and costly (to purchase and operate) lab-based instruments. We propose developing a palm-sized, element-specific, highly-sensitive, battery-operated, smartphone-controlled system for on-site measurement […]
July 21, 2022
Advanced microwave electronics enabling quantum technologies
Summary Superconducting quantum computers require quantum-limited measurements at microwave frequencies in order to implement error correction. Conventionally, this is accomplished using near quantum-limited Josephson Parametric Amplifiers (JPAs). The JPAs require bulky ferrite-based circulators that prevent on-chip integration of the amplifiers with the processor and take up the majority of space and cooling power in the […]
April 1, 2020
Building Blocks for Quantum Neuromorphic Computing: Superconducting Quantum Memcapacitors
Quantum neuromorphic computing (QNC) is a novel method that combines quantum computing with brain-inspired neuromorphic computing. Neuromorphic computing performs computations using a complex ensemble of artificial neurons and synapses (i.e., electrical circuits) to emulate the human brain. QNC may lead to a quantum advantage by realizing these components with quantum memory elements, or memelements, which […]
June 12, 2023