Hybrid on-chip quantum photonics combining deterministic telecom single-photon sources, single-photon detectors with ultra-low loss waveguides

• Applicants: Professor Dr. Peter Michler; Professor Dr. Wolfram Hans Peter Pernice
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469373712

Integrated photonic quantum technologies represent a promising platform for research fields such as simulation of complex phenomena, quantum sensing and quantum information processing. The current proposal aims at revolutionize these fields by hybrid combination of two of the most appealing platforms for quantum photonics: 1) Semiconductor quantum dots for the on-demand generation of non-classical light states. 2) Silicon-based photonics as a key platform for implementing ultra-low loss circuitry. The proposal will tackle technological aspects, like the realization of a novel optimized combination of multiple photonics and quantum photonics structures, as well as fundamental physics aspects as the generation of multi-photon states employing remote sources. We will investigate the impact of the photonic integrated circuits, their waveguides and active optical elements on the propagation and manipulation of non-classical light states. The IHFG pioneered the realization of QDs emitting single, indistinguishable and entangled photons at telecom wavelength, also showing on-demand operation. The WWU is world leading in the implementation of 3D printed optics and implementation of single-photon detectors on waveguides. We implement and investigate the physics of multi-source experiments with important impact on the achievable scalability and experimental complexity going far beyond current state-of-the-art. Our approach allows to fully optimize the QD-based light sources as well as the Si-based circuitry with no limitations posed by the fabrication processes: the non-classical light source and the silicon photonic logic chip will be fabricated separately, then interfaced via 3D printed single mode waveguides. The goals of the project are:1) Realize bright, wavelength tuneable, sources of non-classical light operating at telecom wavelength: this will be enabled combining advanced growth and deterministic lithography at telecom wavelength, i.e. two capabilities pioneered at the IHFG.2) Implement 3D printed interface couplers for the efficient hybrid integration of QDs with Si-based circuitry.3) Realization of ultra-low loss Si-based photonic circuits specifically designed to operate with non-classical light from telecom-wavelength QDs. This will include waveguides, beam splitters, filters, phase shifters and superconducting single-photon detectors.4) Investigation of the generation of multi-photon states via two-photon interference from remote sources.5) Implementation of multi-source chips in order to demonstrate scalability and experimental complexity beyond current state-of-the-art.6) Implementation of quantum simulation operations, i.e. Boson sampling, with multiple on-demand light sources.Achieving the goals highlighted in this project could have an enormous impact for the future development of the above mentioned quantum technologies and broadening the understanding of several aspects of photonic quantum physics.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Simone Luca Portalupi