Nonlinear Quantum Optics

Welcome to our group website!

News: March 13, 2026 We are happy to welcome Fabrice as a new PhD student! Feb 13, 2026 Check out our latest paper - "Mid-IR hyperspectral imaging with undetected photons" Nov 04, 2025 Our latest paper has just been published in Optica Quantum - "Hong-Ou-Mandel effect with two frequency-entangled photons of vastly different color" May 06, 2025 Congratulations to Theresa for the successful defense of her Bachelor thesis! April 11, 2025 We spent three days on a group retreat with the Heeg group in the picturesque nowhere in Brandenburg. How did we end up? With an overview of possible techniques to determine an absorption spectrum, everyone knowing how to pantomime the honey badger, lots of Italian and Brazilian food and a hangover on the last morning. March 01, 2025 We warmly welcome Steven as a new Bachelor student in our group! December 06, 2024 Santa Claus and Christmas party! This year we went to the medieval Christmas market to throw axes and drink mulled wine. Followed by Christmas dinner at a delicious Italian restaurant. [see more]	Research: *Mid-IR sensing* *with undetected photons* *Quantum frequency conversion* *Integrated photonics*

Marlon Placke, Chiara Lindner, Felix Mann, Inna Kviatkovsky, Helen M. Chrzanowski, Hendrik Bartolomaeus, Frank Kühnemann, and Sven Ramelow, "Mid-IR hyperspectral imaging with undetected photons", Optica Quantum 13, 328-335 (2026)
Felix Mann, Helen M. Chrzanowski, Marlon Placke, Felipe Gewers, and Sven Ramelow, "Hong–Ou–Mandel effect with two frequency-entangled photons of vastly different color", Optica Quantum 3, 495-499 (2025)
Felix Mann, Helen M. Chrzanowski, Felipe Gewers, Marlon Placke, and Sven Ramelow, "Noise analysis of a quasi-phase-matched quantum frequency converter and higher-order counter-propagating SPDC", Opt. Express 32, 42225-42239 (2024)
M. Placke, J. Schlegel, F. Mann, P. Della Casa, A. Thies, M. Weyers, G. Tränkle, and S. Ramelow, "Telecom-Band Spontaneous Parametric Down-Conversion in AlGaAs-on-Insulator Waveguides", Laser & Photonics Reviews (2024)
F. Mann, H. M. Chrzanowski, F. Gewers, M. Placke, and S. Ramelow, "Low-noise quantum frequency conversion in a monolithic cavity with bulk periodically poled potassium titanyl phosphate", Phys. Rev. Appl. 20, 054010 (2023)