Ultracold molecules are ideal platforms for many important applications, ranging from quantum simulation1,2,3,4,5 and quantum information processing 6,7 to precision tests of fundamental physics2,8,9,10,11. Producing trapped, dense samples of ultracold molecules is a challenging task. One promising approach is direct laser cooling, which can be applied to several classes of molecules not easily assembled from ultracold atoms12,13. Here, we report the production of trapped samples of laser-cooled CaF molecules with densities of 8 × 107 cm−3 and at phase-space densities of 2 × 10−9, 35 times higher than for sub-Doppler-cooled samples in free space14. These advances are made possible by efficient laser cooling of optically trapped molecules to well below the Doppler limit, a key step towards many future applications. These range from ultracold chemistry to quantum simulation, where conservative trapping of cold and dense samples is desirable. In addition, the ability to cool optically trapped molecules opens up new paths towards quantum degeneracy.
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Micheli, A., Brennen, G. K. & Zoller, P. A toolbox for lattice-spin models with polar molecules. Nat. Phys. 2, 341–347 (2006).
Carr, L. D., DeMille, D., Krems, R. V. & Ye, J. Cold and ultracold molecules: science, technology and applications. New J. Phys. 11, 055049 (2009).
Pupillo, G. et al. Cold atoms and molecules in self-assembled dipolar lattices. Phys. Rev. Lett. 100, 050402 (2008).
Büchler, H. P. et al. Strongly correlated 2D quantum phases with cold polar molecules: controlling the shape of the interaction potential. Phys. Rev. Lett. 98, 060404 (2007).
Blackmore, J. A. et al. Ultracold molecules: a platform for quantum simulation. Preprint at http://arXiv.org/abs/1804.02372v1 (2018).
DeMille, D. Quantum computation with trapped polar molecules. Phys. Rev. Lett. 88, 067901 (2002).
Yelin, S. F., Kirby, K. & Côté, R. Schemes for robust quantum computation with polar molecules. Phys. Rev. A 74, 050301 (2006).
ACME Collaboration Order of magnitude smaller limit on the electric dipole moment of the electron. Science 343, 269–272 (2014).
Kara, D. M. et al. Measurement of the electrons electric dipole moment using YbF molecules: methods and data analysis. New J. Phys. 14, 103051 (2012).
Lim, J. et al. Laser cooled YbF molecules for measuring the electron’s electric dipole moment. Phys. Rev. Lett. 120, 123201 (2018).
Kozyryev, I. & Hutzler, N. R. Precision measurement of time-reversal symmetry violation with laser-cooled polyatomic molecules. Phys. Rev. Lett. 119, 133002 (2017).
Rosa, M. D. Laser-cooling molecules. Eur. Phys. J. D 31, 395–402 (2004).
Kozyryev, I., Baum, L., Matsuda, K. & Doyle, J. M. Proposal for laser cooling of complex polyatomic molecules. ChemPhysChem 17, 3641–3648 (2016).
Williams, H. J. et al. Magnetic trapping and coherent control of laser-cooled molecules. Phys. Rev. Lett. 120, 163201 (2018).
Yan, B. et al. Observation of dipolar spin-exchange interactions with lattice-confined polar molecules. Nature 501, 521–525 (2013).
Ospelkaus, S. et al. Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules. Science 327, 853–857 (2010).
Barry, J. F., McCarron, D. J., Norrgard, E. B., Steinecker, M. H. & DeMille, D. Magneto-optical trapping of a diatomic molecule. Nature 512, 286–289 (2014).
Norrgard, E., McCarron, D., Steinecker, M., Tarbutt, M. & DeMille, D. Sub-millikelvin dipolar molecules in a radio-frequency magneto-optical trap. Phys. Rev. Lett. 116, 063004 (2016).
Steinecker, M. H., McCarron, D. J., Zhu, Y. & DeMille, D. Improved radio-frequency magneto-optical trap of SrF molecules. ChemPhysChem 17, 3664–3669 (2016).
Truppe, S. et al. Molecules cooled below the Doppler limit. Nat. Phys. 13, 1173–1176 (2017).
Anderegg, L. et al. Radio frequency magneto-optical trapping of CaF with high density. Phys. Rev. Lett. 119, 103201 (2017).
McCarron, D. J., Steinecker, M. H., Zhu, Y. & DeMille, D. Magnetically-trapped molecules efficiently loaded from a molecular MOT. Preprint at http://arXiv.org/abs/1712.01462 (2017).
Stellmer, S., Pasquiou, B., Grimm, R. & Schreck, F. Laser cooling to quantum degeneracy. Phys. Rev. Lett. 110, 263003 (2013).
Hu, J. et al. Creation of a Bose-condensed gas of 87Rb by laser cooling. Science 358, 1078–1080 (2017).
Truppe, S. et al. An intense, cold, velocity-controlled molecular beam by frequency-chirped laser slowing. New J. Phys. 19, 022001 (2017).
Devlin, J. A. & Tarbutt, M. R. Three-dimensional doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states. New J. Phys. 18, 123017 (2016).
Grynberg, G. & Courtois, J.-Y. Proposal for a magneto-optical lattice for trapping atoms in nearly-dark states. Europhys. Lett. 27, 41–46 (1994).
Sievers, F. et al. Simultaneous sub-Doppler laser cooling of fermionic 6Li and 40K on the D 1 line: theory and experiment. Phys. Rev. A 91, 023426 (2015).
Burchianti, A. et al. Efficient all-optical production of large 6Li quantum gases using D 1 gray-molasses cooling. Phys. Rev. A 90, 043408 (2014).
Colzi, G. et al. Sub-Doppler cooling of sodium atoms in gray molasses. Phys. Rev. A 93, 023421 (2016).
Kozyryev, I. et al. Sisyphus laser cooling of a polyatomic molecule. Phys. Rev. Lett. 118, 173201 (2017).
Kosicki, M. B., Kedziera, D. & Zuchowski, P. S. Ab initio study of chemical reactions of cold SrF and CaF molecules with alkali-metal and alkaline-earth-metal atoms: the implications for sympathetic cooling. J. Phys. Chem. A 121, 4152–4159 (2017).
Lim, J., Frye, M. D., Hutson, J. M. & Tarbutt, M. R. Modeling sympathetic cooling of molecules by ultracold atoms. Phys. Rev. A 92, 053419 (2015).
Quéméner, G. & Bohn, J. L.. Shielding 2Σ ultracold dipolar molecular collisions with electric fields. Phys. Rev. A 93, 012704 (2016).
Schlosser, N., Reymond, G. & Grangier, P. Collisional blockade in microscopic optical dipole traps. Phys. Rev. Lett. 89, 023005 (2002).
Yavuz, D. D. et al. Fast ground state manipulation of neutral atoms in microscopic optical traps. Phys. Rev. Lett. 96, 063001 (2006).
Endres, M. et al. Atom-by-atom assembly of defect-free one-dimensional cold atom arrays. Science 354, 1024–1027 (2016).
Barredo, D., de Léséleuc, S., Lienhard, V., Lahaye, T. & Browaeys, A. An atom-by-atom assembler of defect-free arbitrary two-dimensional atomic arrays. Science 354, 1021–1023 (2016).
Vuletić, V., Chin, C., Kerman, A. J. & Chu, S. Degenerate Raman sideband cooling of trapped cesium atoms at very high atomic densities. Phys. Rev. Lett. 81, 5768–5771 (1998).
Roos, C. F. et al. Experimental demonstration of ground state laser cooling with electromagnetically induced transparency. Phys. Rev. Lett. 85, 5547–5550 (2000).
Kaufman, A. M., Lester, B. J. & Regal, C. A. Cooling a single atom in an optical tweezer to its quantum ground state. Phys. Rev. X 2, 041014 (2012).
Thompson, J. D., Tiecke, T. G., Zibrov, A. S., Vuletić, V. & Lukin, M. D. Coherence and Raman sideband cooling of a single atom in an optical tweezer. Phys. Rev. Lett. 110, 133001 (2013).
This work was supported by the National Science Foundation (NSF) and Army Research Office (ARO). B.L.A. acknowledges support from NSF Graduate Research Fellowship Program. L.W.C. acknowledges support from Max Planck Harvard Research Center for Quantum Optics. We thank the Greiner group for lending us a 1,064-nm fibre amplifier.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Anderegg, L., Augenbraun, B.L., Bao, Y. et al. Laser cooling of optically trapped molecules. Nature Phys 14, 890–893 (2018). https://doi.org/10.1038/s41567-018-0191-z
Theoretical Study of the FrLi Molecule: Computation of Adiabatic and Diabatic Potential Energy Curves, Spectroscopic Constants, Dipole Moment, Radiative Lifetime and Spectrum Absorption
Arabian Journal for Science and Engineering (2021)
Frontiers of Physics (2021)
Nature Reviews Physics (2020)
Light-induced frequency shifts for the lowest vibrational levels of ultracold Cs2 in the molecular pure long-range $$0_g^-$$ state
Frontiers of Physics (2020)