Integrated Sources of Entangled and Indistinguishable Photons

• Applicants: Professor Dr. Stephan Reitzenstein; Professor Dr. Christian Schneider
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263348684

The transformative nature of quantum optics and quantum information processing research has already changed the way we think about nature and its relation to information. Moreover, devices for secure communications have been commercialized based on the laws of quantum physics. Many of the most spectacular developments in the field have to do with quantum states of light.This project will take the production of these states to the next level in terms of miniaturization and integration and aims at an in-depth understanding of the underlying physical processes. In a III-V semiconductor system we will develop and study a quantum optics platform of nonlinear optical elements, single quantum emitters and other waveguide optical elements. We will take advantage of the fact that resonantly excited quantum dots can emit very clean single photons where subsequent photons are indistinguishable from each other, which is crucial for any use in multi-photon protocols, for example in quantum repeaters. Moreover, we will utilize Bragg-reflection waveguides to facilitate efficient nonlinear conversion of light. The desired process is spontaneous parametric down-conversion, which converts a shorter wavelength pump photon to an entangled pair of photons in the telecommunications wavelength band. Within an on-chip approach we will study and optimize the generation of single and entangled photon pairs by resonantly coupling the output of electrically pumped whispering gallery mode micro-lasers to single quantum dots embedded in adjacent micropillar cavities and Bragg-reflection waveguides. While all of these structures and building blocks have been realized before, no one has achieved the level of integration that we are targeting. Besides technological challenges, there exist a number of exciting physical questions such as an in-depth understanding of the non-linear processes involved in the generation of entangled photon pairs which will be tackled by our project.Our work will set the ground for a quantum optics platform that could revolutionize the way we conduct quantum optics experiments and may in the long run become a new quantum technology.

• DFG Programme: Research Grants
• International Connection: Austria
• Participating Institution: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Participating Person: Professor Dr. Gregor Weihs