2D materials for quantum photonics and light-based qubits

Photons are ideal carriers of quantum information, and quantum photonic devices can be used to realize on-chip and benchtop implementations for a large number of quantum systems and technologies. Many 2D materials such as transition metal dichalcogenide semiconductors intensely interact with light and provide new routes and light-matter interfaces for the creation and manipulation of quantum states of light (i.e., light-based qubits). Emergent properties include single-photon emission, strong nonlinearities, and strong coupling/transduction to other quantum systems. The MonArk Quantum Foundry is investigating many of these properties in 2D materials with the goals of discovering quantum photonic phenomena in new material systems, determining the microscopic origins of quantum photonic phenomena in known materials, investigating 2D heterostructure and nanofabrication schema to control quantum photonic phenomena, and identifying fundamental materials engineering routes to optimize quantum photonic performance in 2D materials.

Quantum Emitters (QEs): On-demand generation of single-photon states and entangled-photon pairs based on 2D material systems are two priority quantum photonic phenomena of the MonArk Quantum Foundry. The preparation, fabrication, and characterization infrastructure of the 2D-QMaPs are supporting team-wide highly collaborative studies that combine expertise in experimental 2D quantum materials characterization, quantum optical spectroscopy, machine learning, nanofabrication, and state-of-the-art density functional theory that seek to address fundamental questions that stand in the way of transforming 2D quantum emitting materials from the laboratory benchtop to industrial applications. For quantum emitter phenomena in 2D quantum materials, the MonArk Quantum Foundry is focusing on three main research strategies:

1. Cryogenic time-resolved nano-optical characterization of QEs: critical fundamental questions about quantum emitter phenomena in 2D semiconductor materials will be investigated using the exfoliation and cryogenic time-resolved spectroscopy and nanoscale scanning probe capabilities of the 2D-QMaPs. The 2D-QMaP characterization techniques will be combined with high-resolution structural characterization to link atomic structure to explicitly identified and characterized QEs, which will inform the development of microscopic and atomistic models that describe QEs in 2D materials. Materials processing techniques such as etching, irradiation to create vacancies, chemical treatments, and annealing will be explored to generate new classes of quantum emitters and optimize the performance of know quantum emitters.

2. QEs in novel 2D materials: many 2D material systems exist, yet only a few have been explored in terms of quantum emitters. Using the 2D-QMaPs samples of unexplored 2D materials will be prepared and investigated for quantum emission phenomena. This work will be heavily informed by predictions from state-of-the-art microscopic models. As an example, the 2D ferroelectrics efforts will dovetail with this thrust, as recent computational studies have predicted the formation of defect states with promising properties for quantum emission phenomena.

3. Enhancing QE performance with heterostructure and device engineering: the capabilities of the 2D-QMaPs will be used to investigate how heterostructure and device engineering can tune the properties and enhance the performance of quantum emitters based on 2D materials. Through heterostructure fabrication combined with nanofabrication – capabilities provided by the 2D-QMaP infrastructure—a vast parameter space exists which can be utilized to achieve high-performance quantum emitters in terms of stability, brightness, and purity.

Valley qubits: With long-lived, coherent valley-spin states, combined with ps optical control, TMD valley-spin qubits are expected to realize extremely high gate fidelity. Gate-defined quantum dots in transition metal dichalcogenides (TMDs) provide a platform for TMD-based quantum technologies that could provide the required quantum memory nodes of a future 2D integrated quantum photonics network. Because TMDs such as WSe2 are ambipolar conductors, device designs are possible in which the left side of the device is electrostatically doped n-type and the right side is made p-type to create single-electron LEDs. These devices could provide on-demand electrically driven single photons for QE applications and an interface between optical and valley quantum information resources