Research

Rydberg Quantum Optics

Our group explores how individual Rydberg atoms and the strong interaction between them can be used to probe and manipulate other quantum systems, in particular few-photon states of light. The rich level structure of Rydberg atoms allows coupling to other systems over a wide frequency range from RF to the optical domain. At the same time, the Rydberg-blockade mechanism based in the strong Rydberg-Rydberg interaction provides an extreme nonlinearity which can ultimately enable control over the coupled systems on the level of single quanta. With this approach, the fundamentally new regime of nonlinear quantum optics (NQO) becomes accessible, where the response of the Rydberg systems depends on the exact number of input photons (or phonons). Ultimately, we aim to achieve full control over light photon by photon and possibly quantized mechanical motion phonon by phonon.

Rubidium Rydberg NQO project

This project explores nonlinear quantum optics in an ultracold gas of Rubidium atoms. The simple level structure of the alkalis and the established techniques for cooling and trapping Rb make this element a natural choice for exploring Rydberg EIT and nonlinear quantum optics. We first demonstrated the manipulation of the quantum statistics of light via Rydberg interaction in 2013 with this setup. Since then, we managed to implement a single-photon transistor, a single-photon absorber, and perform detailed studies of the Rydberg-mediated photon-photon interaction.

Ytterbium Rydberg NQO project

In May 2018 we begun construction of a new experiment apparatus which will combine ultracold Ytterbium atoms with few-photon Rydberg excitation and nonlinear quantum optics. The core goal of this project is to exploit the advantages provided by Yb for realizing large systems of strongly interacting Rydberg polaritons beyond what is currently achieved in alkali gas experiments. Beyond the NQO applications enabled by this new system, we als plan to study in detail the Rydberg physics of this earth-alkaline-like atomic species.