Welcome to the webpage of the research group of Prof. Dr. Simon Stellmer.
"Quantum metrology": that's the art of measuring using phenomena from quantum physics. Specifically, we aim to increase measurement sensitivity beyond of what would be possible in classical systems, and we do this in an interdisciplinary approach.
Latest News
It's the beginning of the new teaching term, and we welcome a range of new group members: Vedang Sumbre starts his master thesis on the zinc project, where he will begin with spectroscopy on the 308-nm transition. Darius Hoyer comes in for an internship project, in which he will design the Sr MOT vacuum chamber and optics layout. Last but not last, Stefan Gessler will equip our tiltmeter with a new temperature stabilization enclosure. Good luck to all of you!
Two new publications from the group: At first, our paper on isotope shifts of the 423-nm transition in calcium recently appeared with Phys. Rev. A. Secondly, we performed a systematic study of dust contamination in a quantum optics lab and derived practical recommendations. The manuscript, written by Bachelor student Jonas Gottschalk, is now available on the arXiv.
Hybrid quantum information networks will require photonic components that can change the color of a photon while leaving the fragile qubit information untouched. The trick is called quantum frequency conversion, and it's an old trick that has been around for a decade or two. In her recent work, Anica played a couple of new tricks: she used gases instead of crystals (crystals are nice but demanding, whereas gases are cheap and easy to handle), she played the trick inside a hollow core fiber, and she used cw light instead of pulsed light to preserve temporal coherence of the photon. All of this became possible through a collaboration with the Max-Planck-Institute for the Science of Light in Erlangen, which provided the fiber (thanks, Michael!), and through the support of Thorsten Peters from TU Darmstadt (thanks, Thorsten!). The manuscript is now available on the arXiv here.
While we all took a few weeks of during the summer, we also used the quiet weeks to push on some of our projects. At first, Philipp finished his Bachelor thesis on the 3D ring laser project: congratulation Philipp! Second, Maanas Kishorekumar Bysani from Imperial College London spent an 10-week internship with us. Maanas set up the optics and electronics packages of a future transportable strontium MOT... stay tuned! Lastly, Simon and Jannik shuttled back and forth to the ROMY observatory near Munich to install new electronics on their ring lasers.
The University of Bonn and the state of NRW jointly operate a geodetic observatory near Todenfeld, a beautiful Eifel village about 30 km east of Bonn. The observatory hosts a range of seismometers and, since two years, one of the world's finest superconducting gravimeters. The gravimeter is operated by our colleagues and friends Jürgen Kusche and Basem Elsaka from the Geodesy Institute just across the street and can measure changes in the Earth's gavitational potential at the level of one in a billion. We now installed a commercial fiber-optic gyroscope right next to the gravimeter as a test system for our home-built ring lasers. Already now, we can sense slow changes in rotation at the level of a few 10 nrad per second, that's about one revolution per year. Both the gravimeter and the gyroscope are sensitive to tilt, which might become our next joined project. Thanks to Jürgen and Basem for hosting us!
