Although this project has been greatly delayed due to the COVID pandemic, we have made substantial steps towards the project goals. We have optically transported Cs and Rb atoms to the science cell of the vacuum chamber (see attached figure of experimental setup). This separate chamber is required to allow for the high optical access requirements for a quantum gas microscope. We have tested the high resolution imaging setup using a ion beam milled test target in the place of atoms and shown that the setup is suitable for the requirements of imaging individual atoms in an optical lattice We are currently in the process of building the optical lattices required for the quantum gas microscope.
In order to image the different atomic species at the same time, we need a trap that separates the different species. Such a trap can be made with an optical lattice. An optical lattice is created by an interference pattern of overlapping laser beams. The high- and low-intensity regions of light created by the interference pattern create a periodic potential for the particles through the optical dipole force. At certain wavelengths the force can be attractive for one atomic species and repulsive for another species. This is determined by the sign of a property of the atom called the polarizability. This polarizability is wavelength dependent.
Working towards this trap we have studied the tune-out wavelength of Cs around 880 nm. At this tune-out wavelength the polarizability of Cs changes sign. In the vicinity of this wavelength is therefore a suitable regime in which to image the RbCs molecules. In this work (Phys. Rev. A 104, 052813 (2021)), we study the polarizability around this tune-out wavelength and precisely measure the location of this tune-out wavelength.
During the course of this fellowship I have also had the opportunity to study RbCs molecules in a separate experiment. This separate experiment does not have the optical access for creating a high resolution imaging system for a quantum gas microscope. However, it is a ideal experiment for studying fundamental properties of RbCs molecules. We have been able to study both molecule-molecule and atom-molecule collisions. Molecule-molecule collisions are important to understand as they are essential for understanding the large loss of molecules over time. Atom-molecule collisions are important as atoms could be used in the future to further cool the molecules. All these studies have advanced the understanding of bi-alkali molecules, and will be important for future molecular quantum gas microscopes.
