A heterogeneous III-V/silicon integration platform for on-chip quantum photonic circuits with single quantum dot devices (1611.07654v1)

Abstract: Photonic integration is an enabling technology for photonic quantum science, offering greater scalability, stability, and functionality than traditional bulk optics. Here, we describe a scalable, heterogeneous III-V/silicon integration platform to produce Si$_3$N$_4$ photonic circuits incorporating GaAs-based nanophotonic devices containing self-assembled InAs/GaAs quantum dots. We demonstrate pure singlephoton emission from individual quantum dots in GaAs waveguides and cavities - where strong control of spontaneous emission rate is observed - directly launched into Si$_3$N$_4$ waveguides with > 90 % efficiency through evanescent coupling. To date, InAs/GaAs quantum dots constitute the most promising solidstate triggered single-photon sources, offering bright, pure and indistinguishable emission that can be electrically and optically controlled. Si$_3$N$_4$ waveguides offer low-loss propagation, tailorable dispersion and high Kerr nonlinearities, desirable for linear and nonlinear optical signal processing down to the quantum level. We combine these two in an integration platform that will enable a new class of scalable, efficient and versatile integrated quantum photonic devices

• The paper demonstrates the integration of InAs/GaAs quantum dots into silicon waveguides, achieving high purity and indistinguishable single-photon emission.
• It introduces a scalable heterogeneous platform that effectively couples active GaAs devices with passive Si circuits via evanescent coupling (>90% efficiency).
• The work provides strong control over quantum dot spontaneous emission rates, paving the way for advanced and complex on-chip quantum photonic circuits.

Overview of a Heterogeneous Integration Platform for On-chip Quantum Photonic Circuits with Quantum Dot Devices

The paper "A heterogeneous III-V/silicon integration platform for on-chip quantum photonic circuits with single quantum dot devices" discusses the development of a scalable, heterogeneous integration platform combining III-V semiconductor materials with silicon photonics. This platform allows for the creation of photonic circuits on silicon (Si) that incorporate GaAs-based nanophotonic devices containing self-assembled InAs/GaAs quantum dots (QDs). These quantum dots are utilized for applications in quantum photonics due to their capacity for generating pure, indistinguishable single photons.

Key Findings and Contributions

1. Quantum Dot Integration: The paper demonstrates the integration of single GaAs waveguides and cavities, containing InAs/GaAs QDs, directly with Si waveguides. The QDs are shown to emit single photons with high purity, brightness, and indistinguishability.
2. Photonic Platform Architecture: The integration platform allows passive Si waveguide circuits to be coupled with active GaAs nanophotonic devices. This enhances versatility and scalability, enabling the realization of complex quantum photonic devices.
3. Evanescent Coupling Efficiency: The research shows single photons emitted from QDs in GaAs devices are coupled efficiently (over 90%) into Si waveguides through evanescent coupling. This high efficiency is crucial for reducing losses that often limit the scaling of photonic quantum circuits.
4. Control of Spontaneous Emission: The paper underscores the strong control over the QD spontaneous emission rate achievable with this integration method. Such control is essential for developing deterministic photon sources necessary for quantum computing applications.
5. Scalability and Fabrication: The platform's fabrication process is designed to be scalable, incorporating photonic integrated circuit technologies that align lithographically defined III-V and silicon devices with sub-100 nm precision.

Implications and Future Directions

The integration of III-V semiconductors with Si photonics provides a pathway to overcome current limitations in quantum photonic circuits, particularly concerning photon flux and integration complexity. This platform enables on-chip quantum dot single-photon sources, which are pivotal for scalable quantum information applications and can potentially lead to advances in quantum computation, simulations, and metrology.

The work outlined in the paper suggests several implications for future research and development:

• Enhanced Photonic Circuit Complexity: By efficiently integrating QDs with low-loss Si waveguides, it is feasible to create more intricate quantum circuits on a chip, enhancing the capability for large-scale quantum computations.
• Exploration of Quantum Interactions: The platform could facilitate studies of quantum-level processes, such as Kerr nonlinearities and optomechanical interactions, furthering our understanding and manipulation of quantum systems.
• Integration with Other Technologies: Future research may focus on integrating this photonic platform with other quantum technologies, such as superconducting detectors and electro-optic modulators, to develop comprehensive on-chip quantum devices.

Overall, the paper presents a comprehensive framework for advancing quantum photonic integration, with significant potential impacts on both theoretical studies and practical applications in quantum technologies. The heterogeneous integration approach represents a substantial step toward realizing practical, scalable quantum photonic circuits.