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Ultracold molecules have many potential applications, ranging from quantum simulation and quantum computing to the creation of novel quantum phases [1]. There is particular interest in polar molecules, which can have long-range anisotropic interactions resulting from their permanent dipoles. A variety of such molecules have been produced at microkelvin temperatures by association of pairs of atoms, or by direct laser cooling. Many applications of ultracold molecules need high phase-space densities. For atoms, this is usually achieved by evaporative or sympathetic cooling. However, high-density samples of ultracold molecules usually undergo collisional loss, due to a variety of short-range mechanisms that may include two-body inelastic or reactive collisions, three-body collisions, or laser-induced loss. Over the last decade, there has been tremendous efforts in understanding the collisional complexes that molecules form at short distances, how they impact chemical reactions, and how we can suppress their formation with shielding methods. Shielding has enabled the achievement of a new regime, a molecular gas dominated by elastic interactions, which can then be cooled to quantum degeneracy to study complex dipolar systems [2].
In this presentation, I will talk about one of the shielding mechanisms using static electric fields for ultracold polar molecules [3-5]. External static electric fields will engineer repulsive interactions based on the dipole-dipole interaction. Using this methodology, the rate of two-body loss processes can be reduced by more than 10 orders of magnitude than the elastic collision rate. This will pave the way for evaporative cooling of polar molecules towards quantum degeneracy.
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