Abstract
Control over all internal and external degrees of freedom of molecules at the level of single quantum states will enable a series of fundamental studies in physics and chemistry1,2. In particular, samples of ground-state molecules at ultralow temperatures and high number densities will facilitate new quantum-gas studies3 and future applications in quantum information science4. However, high phase-space densities for molecular samples are not readily attainable because efficient cooling techniques such as laser cooling are lacking. Here we produce an ultracold and dense sample of molecules in a single hyperfine level of the rovibronic ground state with each molecule individually trapped in the motional ground state of an optical lattice well. Starting from a zero-temperature atomic Mott-insulator state5 with optimized double-site occupancy6, weakly bound dimer molecules are efficiently associated on a Feshbach resonance7 and subsequently transferred to the rovibronic ground state by a stimulated four-photon process with >50% efficiency. The molecules are trapped in the lattice and have a lifetime of 8 s. Our results present a crucial step towards Bose–Einstein condensation of ground-state molecules and, when suitably generalized to polar heteronuclear molecules, the realization of dipolar quantum-gas phases in optical lattices8,9,10.
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Acknowledgements
We thank H. Ritsch, S. Dürr, N. Bouloufa and O. Dulieu for valuable discussions. We are indebted to R. Grimm for generous support and to H. Häffner for the loan of a charge-coupled camera. We gratefully acknowledge financial support by the Austrian Ministry of Science and Research (Bundesministerium für Wissenschaft und Forschung) and the Austrian Science Fund (Fonds zur Förderung der wissenschaftlichen Forschung) in the form of a START prize grant and by the European Science Foundation within the framework of the EuroQUASAR collective research project QuDeGPM and within the framework of the EuroQUAM collective research project QuDipMol. R.H. is supported by a Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme.
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Danzl, J., Mark, M., Haller, E. et al. An ultracold high-density sample of rovibronic ground-state molecules in an optical lattice. Nature Phys 6, 265–270 (2010). https://doi.org/10.1038/nphys1533
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DOI: https://doi.org/10.1038/nphys1533
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