Studying spin systems with ultracold polar molecules
Ultracold polar molecules, with their long-range electric dipolar interactions, are a promising platform for studying correlated many-body phenomena such as quantum magnetism. Recently, we observed spin exchange interactions between KRb molecules in a deep 3D optical lattice [1,2], which is one of the first steps towards studying lattice spin models with polar molecules. Thanks to the long-range dipolar interactions, these observations were possible even though the lattice fillings were quite dilute. Future experiments to probe more sophisticated dynamics or realize novel quantum phases will benefit greatly from higher lattice fillings. By utilizing the quantum statistics and interspecies interactions of the initial quantum gases, we simultaneously load a Mott insulator of Rb and a band insulator of K into a 3D optical lattice. Combined with efficient magnetoassociation and optical state transfer, we realize ground-state molecule filling fractions significantly higher than before . We recently installed a new apparatus which features many technical improvements that will greatly improve our control over, and detection of, the molecular gas.
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 S. A. Moses et al., Science 350, 659 (2015).