Prof. Stephan Götzinger

  • Professor
  • Room: A.3.230
  • Telephone: +49 9131 7133315
  • E-mail

My research is focused on solid-state quantum optics. In the past few years I have, for example, investigated methods to collect single photons with near-unity efficiency. Another emphasis is on techniques which can be used to enhance the interaction of a single photon with a single emitter.

2019

Coherent nonlinear optics of quantum emitters in nanophotonic waveguides

Pierre Türschmann, Hanna Le Jeannic, Signe F. Simonsen, Harald Haakh, Stephan Götzinger, Vahid Sandoghdar, Peter Lodahl, Nir Rotenberg

Nanophotonics 8 1641-1657 (2019) | Journal

Coherent quantum optics, where the phase of a photon is not scrambled as it interacts with an emitter, lies at the heart of many quantum optical effects and emerging technologies. Solid-state emitters coupled to nanophotonic waveguides are a promising platform for quantum devices, as this element can be integrated into complex photonic chips. Yet, preserving the full coherence properties of the coupled emitter-waveguide system is challenging because of the complex and dynamic electromagnetic landscape found in the solid state. Here, we review progress toward coherent light-matter interactions with solid-state quantum emitters coupled to nanophotonic waveguides. We first lay down the theoretical foundation for coherent and nonlinear light-matter interactions of a two-level system in a quasi-one-dimensional system, and then benchmark experimental realizations. We discuss higher order nonlinearities that arise as a result of the addition of photons of different frequencies, more complex energy level schemes of the emitters, and the coupling of multiple emitters via a shared photonic mode. Throughout, we highlight protocols for applications and novel effects that are based on these coherent interactions, the steps taken toward their realization, and the challenges that remain to be overcome.

Coherent coupling of single molecules to on-chip ring resonators

Dominik Rattenbacher, Alexey Shkarin, Jan Renger, Tobias Utikal, Stephan Götzinger, Vahid Sandoghdar

New Journal of Physics 21 062002 (2019) | Journal

We report on cryogenic coupling of organic molecules to ring microresonators obtained by looping subwavelength waveguides (nanoguides). We discuss fabrication and characterization of the chip-based nanophotonic elements which yield a resonator finesse in the order of 20 when covered by molecular crystals. Our observed extinction dips from single molecules reach 22%, consistent with an expected enhancement factor of up to 11 for the molecular emission into the nanoguide. Future efforts will aim at efficient coupling of a handful of molecules via their interaction with a ring microresonator mode, setting the ground for the realization of quantum optical cooperative effects.

Turning a molecule into a coherent two-level quantum system

Daqing Wang, Hrishikesh Kelkar, Diego-Martin Cano, Dominik Rattenbacher, Alexey Shkarin, Tobias Utikal, Stephan Götzinger, Vahid Sandoghdar

Nature Physics 15 483-489 (2019) | Journal

The use of molecules in quantum optical applications has been hampered by incoherent internal vibrations and other phononic interactions with their environment. Here we show that an organic molecule placed into an optical microcavity behaves as a coherent two-level quantum system. This allows the observation of 99% extinction of a laser beam by a single molecule, saturation with less than 0.5 photons and non-classical generation of few-photons super-bunched light. Furthermore, we demonstrate efficient interaction of the molecule–microcavity system with single photons generated by a second molecule in a distant laboratory. Our achievements represent an important step towards linear and nonlinear quantum photonic circuits based on organic platforms.

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