The focus of our research is on two big experiments:
Molecules exhibit a more complex structure and more interesting interactions than single atoms. In our experiment atoms are cooled as an atomic cloud until reaching the ultra-cold regime (µK – nK) for the purpose of combining them afterwards to many thousands of molecules. Their properties are ideal to investigate many-body quantum systems and to gain new basic knowledge in the field of condensed matter and quantum computing. In this case, the combination of rubidium and ytterbium is particularly attractive because the molecules exhibit a large electrical as well as a magnetic dipole moment. These parameters allow us to control the interactions in our quantum system.
The long term goal of this experiment in our research group is the production of RbYb-molecules in the ground state in a three dimensional lattice consisting of light.
Our experiment is part of the research about the basic properties of ytterbium Rydberg atoms using different laser systems. The cooling and trapping of the atoms is the foundation of our measurements.
If the outermost electron of an atom is in a highly excited state with principal quantum numbers higher than 20, the distance to the core is increased. The atom can be 10000 times larger than the ground state atom.
Because of the shielding of the core's charge by the remaining electrons, one will have a structure similar to the hydrogen atom, which is called Rydberg atom. The atom's core and all of its electrons, except the outermost one, act as an ionic core of finite size for the valence electron. The resulting probability for the electron to be in the core is the only deviation from the hydrogen case, described by the quantum defect.
Due to the large electric dipole moment resulting from the distance between the positively charged core and the negatively charged electron, Rydberg atoms are really sensitive to electric fields, which makes them very interesting to study. Because of the long range interactions and the longer lifetimes (µs and higher), effects like the dipole blockade can be analyzed.
The studies of various interactions of ytterbium Rydberg atoms in an optical lattice is the long term goal of this experiment.