Scalable quantum photonic platform based on site-controlled quantum dots coupled to circular Bragg grating resonators

Area of Science:

• Quantum photonics
• Solid-state physics
• Nanotechnology

Background:

• Scalable integration of quantum emitters into photonic nanostructures is crucial for quantum technologies.
• Deterministic fabrication of quantum dots (QDs) with photonic resonators is challenging.

Purpose of the Study:

• To demonstrate a robust and streamlined integration strategy for site-controlled QDs with circular Bragg grating (CBG) resonators.
• To achieve precise spatial alignment for enhanced light extraction and high-performance single-photon sources (SPS).

Main Methods:

• Utilized a buried-stressor-based site-controlled InGaAs QD platform for deterministic growth.
• Fabricated a 6x6 array of site-controlled QD-CBG devices with 100% yield.
• Analyzed device performance based on radial offset, including photon-extraction efficiency (PEE), polarization, linewidth, and indistinguishability.

Main Results:

• Achieved 100% device yield in a 6x6 array, with 35 devices showing simulated PEE > 20%.
• Demonstrated quantitative bounds on spatial alignment tolerances through offset-dependent performance analysis.
• Attained a PEE of 47.1% in the best-aligned device, alongside high single-photon purity (99.58%) and Hong-Ou-Mandel visibility (81%).

Conclusions:

• The site-controlled QD-CBG platform enables reproducible, lithography-compatible fabrication of high-performance SPS.
• This approach offers a scalable and efficient alternative to conventional lithography-based integration methods.
• The study establishes quantitative understanding of emitter-position dependent effects on quantum emission properties.