Dennis joined the group in August 2017 as a PhD student. He works on generation, detection, and application of squeezing at high frequencies. Optical parametric oscillators (OPOs) not only generate squeezing at frequencies within the resonance bandwidth of their cavities (baseband) but also at other longitudinal modes. This means that squeezing can be measured at multiples of the free-spectral-range (FSR) of the OPO cavity yielding a comb structure. During his PhD, Dennis investigates the generation of such squeezing combs and their application in the field of metrology and quantum information.
One of Dennis’ foci is the development and optimisation of such squeezing sources. Together with Jonas, he set up a 200 MHz OPO in a quasi-monolithic approach achieving close to 10 dB of squeezing. Together with Frauke, he works on a 6m OPO with a frequency of 50 MHz.
To detect squeezing at multiples of the FSR, an RF detector is needed. Since these are commercially not available, Dennis developed low noise high-speed homodyne detectors with a close to one quantum efficiency. That has a shot noise to dark noise clearance larger than 10 dB up to 3 GHz.
Currently, Dennis is working on experiments in the field of quantum information. In a first step, he plans to spatially separate sidebands at positive frequencies from their counterpart at negative frequencies and thereby generate Einstein-Podolsky-Rosen states. With these states, further experiments are planned such as measurement-induced entanglement, entanglement swapping and quantum teleportation in space and frequency.