Ultracold molecules promise new directions in quantum science and technology, including advances in precision sensing, quantum simulation, and quantum information. A prerequisite is full quantum state control of molecules. Achieving this ultimate level of control has been challenging due to a rich internal state structure that comprises electronic, vibrational, rotational and spin degrees of freedom. However, it is exactly this rich structure that makes molecules appealing.

In this talk, I will discuss our first research thrust that is directed towards achieving full quantum control of ultracold dipolar molecules and using them for quantum simulation. Over the past years, we have demonstrated atom-by-atom assembly of sodium-potassium ground state molecules, demonstrated quantum state control of rotational states, and revealed that the coherence time of a qubit encoded in the nuclear spin of ultracold molecules can reach coherence times on the scale of a second. Most recently, we have shown that - besides dipolar interactions - van der Waals interactions play a crucial role in ultracold molecules. Molecular van der Walls interactions can be tuned, for example via microwave dressing, and reach significant strength - with important implications for the many-body physics of ultracold molecular ensembles. Currently, we work towards strongly interacting two-dimensional systems of dipolar sodium-cesium molecules, in which it would be exciting to observe the formation of a self-organized dipolar quantum crystal. As a second research thrust, we recently started work on a novel nanophotonic platform to create programmable arrays of ultracold atoms. I will give a brief outline of this project at the end of my talk.