Ultracold field-linked tetratomic molecules

Abstract

Ultracold polyatomic molecules offer intriguing new opportunities in cold chemistry, precision measurements, and quantum information processing, thanks to their rich internal structure. However, their increased complexity compared to diatomic molecules presents a formidable challenge to employ conventional cooling techniques. Here, we demonstrate a new approach to create ultracold polyatomic molecules by electroassociation in a degenerate Fermi gas of microwave-dressed polar molecules through a field-linked resonance. Starting from ground state NaK molecules, we create around $1.1\times 10^3$ tetratomic (NaK)${}_2$ molecules, with a phase space density of $0.040(3)$ at a temperature of $134(3)\text{nK}$, more than $3000$ times colder than previously realized tetratomic molecules. We observe a maximum tetramer lifetime of $8(2)\text{ms}$ in free space without a notable change in the presence of an optical dipole trap, indicating these tetramers are collisionally stable. The measured binding energy and lifetime agree well with parameter-free calculations, which outlines pathways to further increase the lifetime of the tetramers. Moreover, we directly image the dissociated tetramers through microwave-field modulation to probe the anisotropy of their wave function in momentum space. Our result demonstrates a universal tool for assembling ultracold polyatomic molecules from smaller polar molecules, which is a crucial step towards Bose--Einstein condensation (BEC) of polyatomic molecules and towards a new crossover from a dipolar Bardeen-Cooper-Schrieffer (BCS) superfluid to a BEC of tetramers. Additionally, the long-lived FL state provides an ideal starting point for deterministic optical transfer to deeply bound tetramer states.

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Cited by in corpus (13)

• Observation of Bose-Einstein Condensation of Dipolar Molecules
• Three-Body Recombination of Ultracold Microwave-Shielded Polar Molecules
• Magnifying the Wave Function of Interacting Fermionic Atoms
• Collisions of Spin-polarized YO Molecules for Single Partial Waves
• Nonequilibrium quench dynamics of Bose-Einstein condensates of microwave-shielded polar molecules
• Synthetic Mutual Gauge Field in Microwave-Shielded Polar Molecular Gases
• Effective potential and scattering length of shielding polar molecules
• Vibronic coupling limits the use of high-lying electronic states in complex molecules for laser cooling
• Ultracold coherent control of molecular collisions at a Förster resonance
• Observation of modulation-induced Feshbach resonance
• Parity-Doublet Coherence Times in Optically Trapped Polyatomic Molecules
• Strongly dipolar molecular Bose-Einstein condensates: From few- to many-body physics
• Efimov Effect in Ultracold Microwave-Shielded Polar Molecules