{"id":105036,"date":"2020-04-09T13:03:13","date_gmt":"2020-04-09T20:03:13","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2020\/04\/collisional-cooling-of-ultracold-molecules"},"modified":"2020-04-09T13:03:13","modified_gmt":"2020-04-09T20:03:13","slug":"collisional-cooling-of-ultracold-molecules","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2020\/04\/collisional-cooling-of-ultracold-molecules","title":{"rendered":"Collisional cooling of ultracold molecules"},"content":{"rendered":"<p><a class=\"aligncenter blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/collisional-cooling-of-ultracold-molecules.jpg\"><\/a><\/p>\n<p>Since the original work on Bose\u2013Einstein condensation<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 1\" title=\"Anderson, M. H., Ensher, J. R., Matthews, M. R., Wieman, C. E. & Cornell, E. A. Observation of Bose&ndash;Einstein condensation in a dilute atomic vapor. Science 269, 198&ndash;201 (1995).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR1\" id=\"ref-link-section-d130980e394\">1<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"Davis, K. B. et al. Bose&ndash;Einstein condensation in a gas of sodium atoms. Phys. Rev. Lett. 75, 3969&ndash;3973 (1995).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR2\" id=\"ref-link-section-d130980e397\">2<\/a><\/sup>, the use of quantum degenerate gases of atoms has enabled the quantum emulation of important systems in condensed matter and nuclear physics, as well as the study of many-body states that have no analogue in other fields of physics<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 3\" title=\"Bloch, I., Dalibard, J. & Zwerger, W. Many-body physics with ultracold gases. Rev. Mod. Phys. 80, 885&ndash;964 (2008).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR3\" id=\"ref-link-section-d130980e401\">3<\/a><\/sup>. Ultracold molecules in the micro- and nanokelvin regimes are expected to bring powerful capabilities to quantum emulation<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 4\" title=\"Baranov, M. A., Dalmonte, M., Pupillo, G. & Zoller, P. Condensed matter theory of dipolar quantum gases. Chem. Rev. 112, 5012&ndash;5061 (2012).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR4\" id=\"ref-link-section-d130980e405\">4<\/a><\/sup> and quantum computing<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 5\" title=\"DeMille, D. Quantum computation with trapped polar molecules. Phys. Rev. Lett. 88, 067901 (2002).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR5\" id=\"ref-link-section-d130980e409\">5<\/a><\/sup>, owing to their rich internal degrees of freedom compared to atoms, and to facilitate precision measurement and the study of quantum chemistry<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 6\" title=\"Carr, L. D., DeMille, D., Krems, R. V. & Ye, J. Cold and ultracold molecules: science, technology and applications. New J. Phys. 11, 055049 (2009).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR6\" id=\"ref-link-section-d130980e413\">6<\/a><\/sup>. Quantum gases of ultracold atoms can be created using collision-based cooling schemes such as evaporative cooling, but thermalization and collisional cooling have not yet been realized for ultracold molecules. Other techniques, such as the use of supersonic jets and cryogenic buffer gases, have reached temperatures limited to above 10 millikelvin<sup><a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 7\" title=\"Christen, W., Rademann, K. & Even, U. Efficient cooling in supersonic jet expansions of supercritical fluids: CO and CO2. J. Chem. Phys. 125, 174307 (2006).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR7\" id=\"ref-link-section-d130980e418\">7<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 8\" title=\"Weinstein, J. D., deCarvalho, R., Guillet, T., Friedrich, B. & Doyle, J. M. Magnetic trapping of calcium monohydride molecules at millikelvin temperatures. Nature 395, 148&ndash;150 (1998).\" href=\"https:\/\/www.nature.com\/articles\/s41586-020-2141-z#ref-CR8\" id=\"ref-link-section-d130980e421\">8<\/a><\/sup>. Here we show cooling of NaLi molecules to micro- and nanokelvin temperatures through collisions with ultracold Na atoms, with both molecules and atoms prepared in their stretched hyperfine spin states. We find a lower bound on the ratio of elastic to inelastic molecule\u2013atom collisions that is greater than 50\u2014large enough to support sustained collisional cooling. By employing two stages of evaporation, we increase the phase-space density of the molecules by a factor of 20, achieving temperatures as low as 220 nanokelvin. The favourable collisional properties of the Na\u2013NaLi system could enable the creation of deeply quantum degenerate dipolar molecules and raises the possibility of using stretched spin states in the cooling of other molecules.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Since the original work on Bose\u2013Einstein condensation1,2, the use of quantum degenerate gases of atoms has enabled the quantum emulation of important systems in condensed matter and nuclear physics, as well as the study of many-body states that have no analogue in other fields of physics3. Ultracold molecules in the micro- and nanokelvin regimes are [\u2026]<\/p>\n","protected":false},"author":513,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,48,1617],"tags":[],"class_list":["post-105036","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-particle-physics","category-quantum-physics"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/105036","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/513"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=105036"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/105036\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=105036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=105036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=105036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}