Atomically thin quantum light emitting diodes (1603.08795v2)

Abstract: Transition metal dichalcogenides (TMDs) are optically active layered materials providing potential for fast optoelectronics and on-chip photonics. We demonstrate electrically driven single-photon emission from localised sites in tungsten diselenide (WSe2) and tungsten disulphide (WS2). To achieve this, we fabricate a light emitting diode structure comprising single layer graphene, thin hexagonal boron nitride and TMD mono- and bi-layers. Photon correlation measurements are used to confirm the single-photon nature of the spectrally sharp emission. These results present the TMD family as a platform for hybrid, broadband, atomically precise quantum photonics devices.

• The paper presents a novel LED design using graphene, hBN, and TMD layers for stable, electrically driven single-photon emission.
• Photon correlation measurements with a Hanbury Brown and Twiss interferometer confirmed g(2)(0) values well below the classical threshold.
• Spectrum tuning is achieved by replacing WSe2 with WS2, highlighting the integration potential for scalable quantum photonic devices.

Overview of Atomically Thin Quantum Light Emitting Diodes

The paper entitled "Atomically thin quantum light emitting diodes" presents a detailed paper on electrically driven single-photon emission from localized sites in transition metal dichalcogenides (TMDs) such as tungsten diselenide (WSe$_2$) and tungsten disulfide (WS$_2$). The research successfully demonstrates the fabrication of light emitting diode (LED) structures using single-layer graphene, hexagonal boron nitride (hBN), and TMD mono- and bi-layers. Photon correlation measurements confirm the single-photon nature of the spectrally sharp emissions, establishing a new class of quantum photonic devices based on the TMD family.

Key Contributions and Results

The paper contributes significantly to the field of quantum photonics by showcasing the all-electrical generation of single photons via atomically layered materials. Some of the critical findings and methodologies include:

1. Device Structure and Fabrication: The research team developed an LED comprising layers of single-layer graphene, hexagonal boron nitride, and TMDs. The heterostructure design features single tunneling junctions and offers advantages such as broadband, high-speed operation, and compatibility with silicon-based platforms.
2. Single-Photon Emission: Quantum emitters in WSe$_2$ were shown to produce single photons electrically, operating efficiently under low currents. Quantum light emission was also achieved from localized sites within the monolayer WSe$_2$, which were identified via highly localized emission in EL maps.
3. Measurement Techniques: The single-photon nature of emissions was analyzed using a Hanbury Brown and Twiss interferometer. The intensity-correlation function, $g^{(2)}(0)$, was significantly below the classical threshold, indicating robust single-photon emission characteristics.
4. Spectrum Manipulation: Replacing WSe$_2$ with WS$_2$ enabled the production of single-photon emissions in different spectral regions, thus demonstrating the flexibility of the method for exploring various host materials and spectral ranges.
5. Material Characteristics and Integration Potential: The proposed TMD-based QLED design exploits the unique optical properties of TMDs, integrating them effectively into photonic circuits due to their atomically precise interfaces and active optoelectronic capabilities.

Implications and Future Directions

The findings highlight promising directions for developing hybrid photonic devices employing layered materials. The potential implications pertain to scalable quantum technologies, where these QLEDs could serve as pivotal components:

• Scalability and Integration: The atomically thin nature of the devices aligns with trends in miniaturization, suggesting facile integration into existing electronic and photonic infrastructure, particularly in on-chip systems.
• Enhanced Device Functionality: The tunability of single-photon emission and the possibility of coupling with other quantum systems, such as rubidium transitions and vacancies in diamond, provide experimental pathways to advanced quantum communication channels and hybrid systems.
• Future Research Prospects: Further investigations may focus on optimizing charge injection mechanisms, reducing emitter linewidth through gating and encapsulation, and exploring other TMDs for broader spectral coverage. Electrostatic modulation strategies might advance the control over localized excitonic states, potentially facilitating applications like quantum entanglement and quantum cryptography.

In conclusion, this paper presents compelling evidence for TMDs as a viable platform for developing next-generation quantum light sources, integrating seamlessly with quantum circuitry while expanding the functional reach of photonic technologies. The versatility and precision offered by atomically thin layers underpin the importance of this research in the continued evolution of quantum photonics.