Microscopy of Ultracold Molecules

Recent years have seen rapid progress in creating and studying ultracold gases of polar molecules. These molecules are attractive candidates for quantum simulation of many-body systems, such as the XXZ model of quantum magnetism, due to their long-range anisotropic interactions and rich internal structure. We have developed a new apparatus to perform site-resolved quantum gas microscopy on strongly-interacting dipolar ²³Na⁸⁷Rb molecules confined within a 2D optical lattice. We form the molecules by coherently assembling sodium and rubidium atoms from atomic Bose-Einstein condensates. Our experiment features in-vacuum electrodes to tune the interactions between the molecules as well as a high-resolution objective for site-resolved imaging. 

Observation of the Hanbury Brown and Twiss Effect with Ultracold Molecules

Rosenberg, J. S., Christakis, L., Guardado-Sanchez, E., Yan, Z. Z., & Bakr, W. 
arXiv:2111.09426.

Measuring the statistical correlations of individual quantum objects provides an excellent way to study complex quantum systems. Ultracold molecules represent a powerful platform for quantum science due to their rich and controllable internal degrees of freedom. However, the detection of correlations between single molecules in an ultracold gas has yet to be demonstrated. Here we observe the Hanbury Brown and Twiss effect in a gas of bosonic ²³Na⁸⁷Rb, enabled by the realization of a quantum gas microscope for molecules. We detect the characteristic bunching correlations in the density fluctuations of a 2D molecular gas released from and subsequently recaptured in an optical lattice. The quantum gas microscope allows us to extract the positions of individual molecules with single-site resolution. As a result, we obtain a high-contrast two-molecule interference pattern with a visibility of 54(13)%. While these measured correlations arise purely from the quantum statistics of the molecules, the demonstrated capabilities pave the way toward site-resolved studies of interacting molecular gases in optical lattices.