Generation and control of polarization-entangledphotons from GaAs island quantum dotsby an electric field

摘要

Semiconductor quantum dots are potential sources for generating polarization-entangledphotons efficiently. The main prerequisite for such generation based on biexciton–excitoncascaded emission is to control the exciton fine-structure splitting. Among various techniquesinvestigated for this purpose, an electric field is a promising means to facilitate the integrationinto optoelectronic devices. Here we demonstrate the generation of polarization-entangledphotons from single GaAs quantum dots by an electric field. In contrast to previous studies,which were limited to In(Ga)As quantum dots, GaAs island quantum dots formed by athickness fluctuation were used because they exhibit a larger oscillator strength and emit lightwith a shorter wavelength. A forward voltage was applied to a schottky diode to control thefine-structure splitting. We observed a decrease and suppression in the fine-structure splittingof the studied single quantum dot with the field, which enabled us to generate polarizationentangled photons with a high fidelity of 0.72±0.05.