Optical pumping and initialization of a hole spin in site-controlled InGaAs pyramidal quantum dots

Abstract

We investigate site-controlled In${}_{0.25}$Ga${}_{0.75}$As quantum dots in (111)B GaAs pyramidal recesses as spin qubits. Combining scanning confocal cryomicroscopy, magneto-photoluminescence studies and resonant excitation, we identify and isolate a positively charged exciton with a hole-spin in its ground state. Application of a strong 5 T magnetic field parallel to the growth axis, induces a fourfold splitting of the energy levels of the positively charged exciton creating an optically addressable double-lambda system. We combine weak above-band and resonant excitation to demonstrate spin pumping and high-fidelity spin initialization through all four optical transitions and study the system behavior as a function of the resonant driving strength showing the existence of a robust spin that can be optically pumped and initialized. These results demonstrate the potential of these quantum dots for precise spin manipulation and their relevance for future quantum hardware.

6 Pages, 4 Figures

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Cited by in corpus (1)

• Self-aligned pillar arrays embedding site-controlled single quantum dots for enhanced non-classical light emission