Solid-State Source of Entangled Photons

Quantum dot based single photon emitter is operability above liquid nitrogen temperature

Here we report the first GaAs/AlGaAs quantum dots grown by the droplet etching and nanohole infilling method, emitting single photons with a narrow wavelength distribution (736.2 ± 1.7 nm) close to the zero-phonon line of silicon-vacancy centers. Polarization entangled photons are generated via the biexciton–exciton cascade with a fidelity of (0.73 ± 0.09). High single photon purity is maintained from 4 K up to 80 K , therefore making this hybrid system technologically attractive for real-world quantum photonic applications. Nanoholes of homogeneous depth were formed during Al droplet etching, which together with the deposition of nominally 0.56 nm GaAs results in a narrow wavelength distribution of (736.2 ± 1.7) nm. Both neutral X and XX peaks are clearly distinguished by measuring either their linear polarization state or their second-order cross-correlation functions. Both X and XX emit pure single photons, which is a prerequisite for quantum information processing. The entanglement fidelity above the classical limit of 0.5 shows that these GaAs QDs are polarization-entangled light sources with a strong potential for coupling to SiV-center-based quantum memories.

Original article:

X. Cao, J. Yang, T. Fandrich, Y. Zhang, E. P. Rugeramigabo, B. Brechtken, R. J. Haug, M. Zopf, and F. Ding: A Solid-State Source of Single and Entangled Photons at Diamond SiV-Center Transitions Operating at 80KNano Lett. 2023, 23, 6109−6115
DOI: 10.1021/acs.nanolett.3c01570