Ultracold LiCr: a new pathway to quantum gases of paramagnetic polar molecules

Abstract

Quantum gases of doubly-polar molecules represent appealing frameworks for a variety of cross-disciplinary applications, encompassing quantum simulation and computation, controlled quantum chemistry and precision measurements. Through a joint experimental and theoretical study, here we explore a novel class of ultracold paramagnetic polar molecules combining lithium alkali and chromium transition metal elements. Focusing on the specific bosonic isotopologue ${}^6$Li${}^{53}$Cr, leveraging on the Fermi statistics of the parent atomic mixture and on suitable Feshbach resonances recently discovered, we produce up to $50\times 10^3$ ultracold LiCr molecules at peak phase-space densities exceeding 0.1, prepared within the least-bound rotationless level of the LiCr electronic $sextet$ ground state $X^6{\Sigma }^{+}$. We thoroughly characterize the molecular gas, demonstrating the paramagnetic nature of LiCr dimers and the precise control of their quantum state. We investigate their stability against inelastic processes and identify a parameter region where pure LiCr samples exhibit lifetimes exceeding 0.2 s. Parallel to this, we employ state-of-the-art quantum-chemical calculations to predict the properties of LiCr ground and excited electronic states. We identify efficient paths to coherently transfer weakly-bound LiCr dimers to their absolute ground state, to deliver ultracold gases of doubly-polar molecules with significant electric (3.3 D) and magnetic ($5{\mu }_{\text{B}}$) dipole moments.

arXiv comment27 pages, 19 figures, 8 main sections, 6 appendices and 90 references

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Cited by in corpus (12)

• Quantum mixtures of ultracold gases of neutral atoms
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• Competing few-body correlations in ultracold Fermi polarons
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• Variational approach to open quantum systems with long-range competing interactions
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• Strongly dipolar molecular Bose-Einstein condensates: From few- to many-body physics
• Ultracold high-spin $\Sigma$-state polar molecules for new physics searches