Deterministic positioning of circular Bragg gratings using atomic force lithography for high-performance quantum dot light sources

Spin Qubit is a semiconducting qubit approach for quantum computing hardware. Source: latex text.

Abstract

Semiconductor quantum dots (QDs) grown by molecular beam epitaxy are excellent quantum emitters, but their random spatial distribution hinders deterministic coupling to optical microcavities. We demonstrate a room-temperature atomic force microscopy (AFM)-assisted nano-oxidation lithography technique enabling QD positioning with a radial displacement of $51(28)$ nm. Free-standing asymmetric circular Bragg gratings incorporating AFM-positioned GaAs QDs exhibit a $245$-fold photoluminescence enhancement and fine-structure splitting (FSS) comparable to bulk QDs. Polarization-resolved spectroscopy and finite-difference time-domain simulations show robust emission for displacements up to $50$ nm (Stokes parameter $|S|<0.05$ ). The devices display stable FSS and polarization imbalance below $5\%$ , confirming precise, reproducible alignment and potential for high fidelity devices. This scalable approach enables deterministic integration of high-performance QDs with photonic cavities, advancing practical quantum light sources for quantum information technologies.

Key Findings

Links

• arXiv: 2605.03672

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