Collisional Cooling of Ultracold Molecules

Abstract

Since the original work on Bose-Einstein condensation, quantum degenerate gases of atoms have allowed the quantum emulation of important systems from condensed matter and nuclear physics, as well as the study of novel many-body states with no analog in other fields of physics. Ultracold molecules in the micro- and nano-Kelvin regimes promise to bring powerful new capabilities to quantum emulation and quantum computing, thanks to their rich internal degrees of freedom compared to atoms. They also open new possibilities for precision measurement and the study of quantum chemistry. Quantum gases of atoms were made possible by collision-based cooling schemes, such as evaporative cooling. For ultracold molecules, thermalization and collisional cooling have not been realized. With other techniques such as supersonic jets and cryogenic buffer gases, studies have been limited to temperatures above 10 mK. Here we show cooling of NaLi molecules at micro- and nano-Kelvin temperatures through collisions with ultracold Na atoms, both prepared in their stretched hyperfine spin states. We find a lower bound on the elastic to inelastic collision ratio between molecules and atoms greater than 50 -- large enough to support sustained collisional cooling. By employing two stages of evaporation, we increase the phase-space density (PSD) of the molecules by a factor of 20, achieving temperatures as low as 220 nK. The favorable collisional properties of a Na and NaLi mixture show great promise for making deeply quantum degenerate dipolar molecules and suggest the potential for such cooling in other systems.

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Cited by in corpus (64)

• Dipolar physics: A review of experiments with magnetic quantum gases
• Evaporation of microwave-shielded polar molecules to quantum degeneracy
• Observation of Bose-Einstein Condensation of Dipolar Molecules
• Probing site-resolved correlations in a spin system of ultracold molecules
• Dipolar evaporation of reactive molecules to below the Fermi temperature
• Observation of Collisions between Two Ultracold Ground-State CaF Molecules
• Quantum state manipulation and cooling of ultracold molecules
• Sub-Doppler Cooling and Compressed Trapping of YO Molecules at $\mu$K Temperatures
• Bimolecular chemistry in the ultracold regime
• Laser cooled molecules
• Collisions of ultracold molecules in bright and dark optical dipole traps
• Self-bound dipolar droplets and supersolids in molecular Bose-Einstein condensates
• Control of reactive collisions by quantum interference
• Atomic Bose-Einstein condensate to molecular Bose-Einstein condensate transition
• Ultracold Sticky Collisions: Theoretical and Experimental Status
• Laser cooling for quantum gases
• Collisions Between Ultracold Molecules and Atoms in a Magnetic Trap
• A Feshbach resonance in collisions between ultracold ground state molecules
• Quantum control of molecules for fundamental physics
• Polarization Enhanced Deep Optical Dipole Trapping of $\Lambda$-cooled Polar Molecules
• Evidence for association of triatomic molecule in ultracold ${}^{23}$Na${}^{40}$K and ${}^{40}$K mixture
• Optical cycling of AlF molecules
• Magnetic Feshbach resonances in collisions of ${}^{23}$Na${}^{40}$K with ${}^{40}$K
• Highly polar molecules consisting of a copper or silver atom interacting with an alkali-metal or alkaline-earth-metal atom
• Quantum state resolved molecular dipolar collisions over four decades of energy
• Diatomic molecules of alkali-metal and alkaline-earth-metal atoms: interaction potentials, dipole moments, and polarizabilities
• Ab initio properties of the NaLi molecule in the $a^3{\Sigma }^{+}$ electronic state
• Spectroscopy on the $A^1\Pi \leftarrow X^1{\Sigma }^{+}$ Transition of Buffer-Gas Cooled AlCl
• Quantum spin state selectivity and magnetic tuning of ultracold chemical reactions of triplet alkali-metal dimers with alkali-metal atoms
• Exploring ultracold collisions in ${}^6$Li-${}^{53}$Cr Fermi mixtures: Feshbach resonances and scattering properties of a novel alkali-transition metal system
• Stereodynamic control of cold rotationally inelastic CO + HD collisions
• Resonant control of elastic collisions between ${}^{23}$Na${}^{40}$K molecules and ${}^{40}$K atoms
• Hyperfine-to-rotational energy transfer in ultracold atom-molecule collisions
• Spectrum of Feshbach resonances in NaLi $+$ Na collisions
• Preparation of a quantum degenerate mixture of ${}^{23}$Na${}^{40}$K molecules and ${}^{40}$K atoms
• Electric-field-controlled cold dipolar collisions between trapped CH${}_3$F molecules
• Ab initio calculation of the spectrum of Feshbach resonances in NaLi + Na collisions
• Probing low-energy Lorentz violation from high-energy modified dispersion in dipolar Bose-Einstein condensates
• Accurate theoretical determination of the ionization potentials of CaF, SrF, and BaF
• Photoassociation of ultracold long-range polyatomic molecules
• Signatures of Non-universal Quantum Dynamics of Ultracold Chemical Reactions of Polar Alkali-dimer Molecules with Alkali-metal Atoms: Li(${}^2$S) +NaLi($a^3{\Sigma }^{+}$) $\to$ Na(${}^2$S) + Li${}_2$($a^3{\Sigma }_u^{+}$)
• General classification of qubit encodings in ultracold diatomic molecules
• Full-dimensional quantum scattering calculations on ultracold atom-molecule collisions in magnetic fields: The role of molecular vibrations
• Low-energy collisions between carbon atoms and oxygen molecules in a magnetic trap
• Radiative Decay Rate and Branching Fractions of MgF
• Observation of Microwave Shielding of Ultracold Molecules
• Sympathetic cooling and slowing of molecules with Rydberg atoms
• Hyperfine dependent atom-molecule loss analyzed by the analytic solution of few-body loss equations
• Symmetry breaking in sticky collisions between ultracold molecules
• Collisions in a dual-species magneto-optical trap of molecules and atoms
• The chemistry of AlF and CaF production in buffer gas sources
• Nuclear spin relaxation in cold atom-molecule collisions
• A ship-in-a-bottle quantum gas microscope setup for magnetic mixtures
• Ultracold molecular collisions in magnetic fields: Efficient incorporation of hyperfine structure in the total rotational angular momentum representation
• Spin Squeezing with Itinerant Dipoles: A Case for Shallow Lattices
• Ultracold Interactions between Ions and Polar Molecules
• Long-range interactions of aromatic molecules with alkali-metal and alkaline-earth-metal atoms
• Broad Feshbach resonance with a large background scattering length in a fermionic atom-molecule mixture
• A hybrid quantum system formed by trapping atoms in the near-field of a levitated nanosphere
• Molecule-molecule and atom-molecule collisions with ultracold RbCs molecules
• Harvesting entanglement from the Lorentz-violating quantum field vacuum in a dipolar Bose-Einstein condensate
• Invariance of quantum scattering rate coefficients to anisotropy of atom-molecule interactions
• Metastable ferromagnetic clusters in dissipative many-body systems of polar molecules
• Strongly dipolar molecular Bose-Einstein condensates: From few- to many-body physics