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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Fundamentals of Optics and Photonics

Open Positions

Master and PhD project: Quantum interfaces between atoms/molecules and nanophotonic waveguides

One of the overarching goals of our research is the control and manipulation of light at the level of individual photons. To reach this fundamental level of control, the light has to be strongly coupled to quantum emitters such as laser-cooled atoms or single molecules. By controlling the internal state of the atoms and making use of their inherent ultra-strong optical nonlinearity we can modify the quantum properties of light. When tailoring this fundamental interaction, we can realize different quantum nanophotonic applications and devices including, for example, quantum memories for light, photon number-dependent filters and routers, as well as sources of non-classical light like single-photon and entangled photon pair sources.

In order to reach the strong light-atom interaction required for our experiments, we couple single atoms, small ensembles of laser-cooled atoms, or single molecules to nanophotonic waveguide structures. Those include optical nanofibers or whispering-gallery-mode resonators that we fabricate in our group. These structures guide light by total internal reflection. At the same time, a large fraction of the light propagates outside the waveguide as evanescent field, where we can interface it with optically trapped atoms, single molecules and other (quantum) emitters. The strong confinement of the propagating light allows us to reach strong light-matter coupling which required for next generation quantum photonic application.

Figure 1: Optical nanofibers (top) and whispering-gallery-mode (WGM) resonators (bottom) as they are realized in our group. Both systems are made from standard optical fibers that are tapered down to a waist of only about 500 nm diameter for the nanofibers  (top) and about 30 µm for the case of WGM resonators (bottom).

We currently are looking for motivated Master and PhD students that are interested in joining our research on quantum nanophotonics. We offer projects that focus on different aspects of nanophotonic light-matter interfaces. Our projects include, e.g., trapping and interfacing of laser cooled atoms with evanescent fields of optical nanofibers or optical whispering-gallery-mode resonators. Other projects focus on the realization of quantum protocols or the study of light-matter interaction under these extreme circumstances.

Research fields: Our projects ecompasse the scientific fields of quantum optics, (nano-) photonics, physics of cold atoms, laser physics, nonlinear optics, 2D materials



For information and details please contact:

Dr. Jürgen Volz (juergen.volz@hu-berlin.de)
Dr. Philipp Schneeweiss (philipp.schneeweiss@hu-berlin.de).