Take this list of upcoming projects as a rough outline only, and approach us if you feel unsure about any of them or if you want to do something different with us.
Optical nonlinearities in atomic vapours for narrowband photon pair generation
Practical quantum information systems will require the interaction between different physical carriers of quantum information, and the interfacing with photons as the one system most suitable for transport is a must. However, existing photon sources both for single photons and pairs exhibit a too large optical bandwidth for efficient interfacing to atoms and molecules. The aim of this project is to investigate the suitability of the huge optical nonlinearities of an atomic vapor for creating photon pairs with a narrow optical bandwidth, and possibly the setup of such a source.
Minimal quantum state estimation for multiphoton states (=>4)
The process of reconstructing an unknown state from a finite set of measuremets is known as quantum tomography. In a scenario where each copy of the state is part of a limited resource, this reconstruction process should be as efficient as possible. The project will combine building a compactified optical setup and theoretically evaluating optimal detection strategies to bound the estimated state with a minimum number of photons detected. The kit will eventually be used to evaluate the quality of specific 4-photon states produced by parametric down-conversion.
High numerical aperture optics
While most lenses are of sperical shape, aspherical lenses can overcome the limitations in the focusing properties of normal lenses, and thus provide a much tighter focusing with a single element. In one of the experiments we use such aspherical lenses to tightly focus a light beam onto a single atom to study the elementary interaction between light and matter. In this project, a the shape for a lens for this purpose should be designed, taking into account mode overlap and polarization properties. First, existing lens designs should be investigated with numerical methods that combine wave and ray optics. Then, a design of a lens with ultra-high NA should be attempted. Depending on how things work out, focusing properties of the design could be verified on the real device experimentally e.g. with interferometric techniques.
