Generation and control of polarization-entangled photons from GaAs island quantum dots by an electric field

• Published in: Nature communications Vol. 3; no. 1; p. 661
• Main Authors: Ghali, Mohsen, Ohtani, Keita, Ohno, Yuzo, Ohno, Hideo
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 07.02.2012; Nature Pub. Group
• Subjects: Arsenicals - chemistry; Electricity; Electronics; Gallium - chemistry; Light; Nanotechnology - methods; Oscillometry - methods; Photons; Physics - methods; Quantum Dots; Scattering, Radiation; Semiconductors; Spectrophotometry - methods; Time Factors
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1657

Semiconductor quantum dots are potential sources for generating polarization-entangled photons efficiently. The main prerequisite for such generation based on biexciton-exciton cascaded emission is to control the exciton fine-structure splitting. Among various techniques investigated for this purpose, an electric field is a promising means to facilitate the integration into optoelectronic devices. Here we demonstrate the generation of polarization-entangled photons 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 a thickness fluctuation were used because they exhibit a larger oscillator strength and emit light with a shorter wavelength. A forward voltage was applied to a Schottky diode to control the fine-structure splitting. We observed a decrease and suppression in the fine-structure splitting of the studied single quantum dot with the field, which enabled us to generate polarization-entangled photons with a high fidelity of 0.72 ± 0.05.