Quantum Cafe: Sebastian Will
Title: Synthetic Dipolar Quantum Matter
Abstract:It has been a long quest in ultracold quantum science to realize many-body systems with strong and tunable long-range interactions that reach beyond the typical contact interactions of ultracold atoms. We have recently created the first ultracold gases of dipolar NaCs molecules [1-3]. NaCs has a large electric dipole moment (4.6 Debye). This allows us to realize dipole-dipole interactions with an effective range that is significantly larger than typical interparticle spacings, which gives us access deep into the strongly interacting regime. In addition, via microwave shielding, we have demonstrated a dramatic reduction in lossy two-body collisions between molecules – which have been the prevalent challenge in the field for the past decade – by 3 orders of magnitude. We now observe lifetimes in molecular samples on the order of one second, which makes ultracold gases of NaCs a “fully usable” quantum liquid. This new form of dipolar quantum matter should allow us to study new emergent quantum phases in 2D, to realize extended Hubbard models, and open up new avenues for quantum simulation of quantum magnetism.
 “Overlapping Bose-Einstein Condensates of Na and Cs,” C. Warner et al., Phys. Rev. A 104, 033302 (2021)
 “A High Phase-Space Density Gas of NaCs Feshbach Molecules,” A. Lam et al., Phys. Rev. Research 4, L022019 (2022)
 “Ultracold Gases of Dipolar NaCs Ground State Molecules,” I. Stevenson et al. arXiv:2206.00652 (2022)