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Jonas joined the group as PhD student in December 2016. Before, he wrote his master thesis in the group from Prof. Benno Willke and built a laser power stabilization for the AEI 10m Prototype. He published the results of his thesis in Optics Letters. [Jonas Junker, Patrick Oppermann, and Benno Willke, Opt. Lett. 42, 755-758 (2017)]
In the first years of his PhD, Jonas focused on the generation of degenerated high-frequency squeezed states of light with a sub-threshold optic parametric oscillator (OPO). He worked together with Dennis on a new experimental approach to increase the signal-to-noise ratio in cavity spectroscopy. In this experiment, technical noise sources are avoided by frequency-modulation techniques and the quantum noise floor is reduced by superimposing the signal with non-classical states of light. Jonas and Dennis published the results of this experiment in Optics Express. [Citation to be added]
Currently, Jonas works on the generation of non-degenerated squeezed states of light. He and Dennis want to discover the entanglement character of these squeezed light fields with different methods. Dennis starts with single-mode squeezing and induced the entanglement via the specific measurement method. Jonas has set up a polarisation non-degenerated two-mode squeezer in our new HITec lab, with which a full Gaussian state estimation seems to be feasible.
Next, Jonas is interested in realizing the first all optical Coherent Quantum Noise Cancellation (CQNC) experiment together with Bernd. In this approach quantum radiation pressure noise couples into the measurement via a micro-oscillator optomechanically. In order to evade this back-action noise an effectively negative-mass oscillator is needed which requires a two-mode down conversion process. A well performing and understood two-mode squeezer paves the way to realize this negative-mass oscillator and thus CQNC.