E5: Collisions of polar fermionic NaK molecules

This project aims at the creation of a quantum degenerate gas of dipolar fermionic ²³Na⁴⁰K molecules and the experimental investigation of collisional few-body properties in the resulting Fermi gas of chemically stable NaK molecules. Understanding the interactions and their control on the few-body level is an important prerequisite for the long-term goal – the study of strongly correlated many-body system of dipolar fermionic molecules. The choice of the molecule is motivated by the relatively large electric dipole moment of 2,7 Debye for the rotational and vibrational ground state, the possibility to switch between cooling of a fermionic or a bosonic potassium isotopes and therefore bosonic and fermionic molecules in the far future and the favorable chemical properties of the low-lying vibrational states of NaK in the electronic ground molecular potential. NaK molecules are expected to be stable against two-body collisional decay via chemical reactions since the reaction path is energetically forbidden for the extremely low collisional energies achieved in ultracold molecular quantum gases. This is in contrast to the pioneering experiments with KRb where chemical reactions have been energetically allowed.

Based on the creation of a quantum gas of polar fermionic NaK molecules, we will study scattering properties of fermionic dipolar NaK molecules. First studies will concentrate on the scattering properties of the rovibrational ground state complementing studies on reactive scattering of dipolar fermions of former project E3 and non-reactive scattering of dipolar bosonic molecules of project E4. Furthermore, we will study the transition from non-reactive to reactive scattering of polar molecules by means of vibrational and rotational excitation and the control of these processes by means of custom designed external confining potentials and dressing fields