Ultrabright sources of single and entangled photon pairs

• Applicant: Professor Dr. Peter Michler
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258767146

The aim of this project is the fabrication of optically pumped ultrabright sources of indistinguishable single and entangled photons in the near infrared spectral range and optically and electrically pumped single photon sources in the red spectral range. The first goal will be ultimately achieved by the combination of a newly designed cavity structure including positioned quantum dots (QD), waveguide coupling and resonant excitation techniques. Therefore, InAs/GaAs quantum dots embedded in high reflective DBR structures will be precisely placed with nanometer accuracy into micropillars. Then tapered one-dimensional nanowires will be connected to these pillars to enable resonant side-excitation with a high laser stray-light suppression. With this schema, we expect to establish a very bright source of entangled photons with a high fidelity and low dephasing. The second goal will be the realization of an ultrabright electrically driven single photon source in the visible red spectral range with GaInP/AlGaInP material system. Here also quantum dots, this time InP QDs, will be embedded into high reflective DBRs, which are now doped to allow the electrical contacting. Then, either pillar structures or mesas for resonant cavity LEDs (RC-LEDs) with the above-mentioned precise accuracy will be formed. The RC-LEDs will additionally receive a narrow oxide aperture to ensure a low current flow only through the single QD in the middle of the device. After finalizing both types of structures, an electrically driven source with a high GHz repetition rate, high collection efficiency and low background will be available. These challenging goals can only be realized by the present cooperation of the world leading groups in the fabrication and characterization of these kind of photon sources. Special key qualifications are the in-situ lithography process developed in Pascale Senellarts group and the side-excitation technique for resonant exciton and biexciton preparation pioneered by Peter Michlers group in Stuttgart.

• DFG Programme: Research Grants
• International Connection: France
• Participating Person: Professorin Dr. Pascale Senellart