Multisource on-chip quantum photonics with tunable low-noise quantum dots

• Applicant: Professor Dr. Peter Michler
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 425333704

The aim of this proposal is to realize on-chip quantum photonics employing strain-tunable, low-noise GaAs quantum dots (QDs) obtained by droplet etching epitaxy (DEE) and embedded into diode structures and novel photonic structures: the main goal is represented by reaching the holy grail of integrated quantum photonics, i.e. ideal two-photon interference from remote sources. Our goals will be realized fabricating devices where multiple, separate QDs can be wavelength tuned independently, via optimized micro-machined piezoelectric actuators. A careful design of the miniaturized actuators will be first performed, to ensure the strain transfer to the QDs embedded in photonic structures. With these devices, it will be possible to tune at the same wavelength multiple emitters. The use of diodes (p-i-n and n-i-n) will allow for drastically reducing the spectral noise in the QDs emission, enabling near-unity interference visibility with remote sources. A key point for the success of the project will be ensuring high coupling of the QD light to the single mode waveguide. For this purpose, we will make use of waveguides fully surrounded by oxide, combined with novel “bowtie” photonic resonators based on a modified “hourglass” design. Near-unity coupling will be key to achieve high source brightness, as well as to enable the investigation of collective effects such as superradiance. Photon mediated coupling among multiple emitters will be targeted. Finally, novel (In)GaAs DEE QDs will be investigated as a route to extend the operation wavelength of our devices to values allowing lower losses and increased tolerance to fabrication imperfection. All QD ensembles will be grown to have their average wavelength matching that of atomic transitions (Rb D1 and Cs D1 and D2), which, in the future, will provide the possibility of interfacing with atomic ensembles, as well as setting precise operation wavelengths given by atomic standards for frequency stabilization and inter-chip links.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partners: Professor Dr. Armando Rastelli; Dr. Sandra Stroj