Editing Laser cooling (section)

==== Molecules ====
[[File:Laser cooled molecules.svg|thumb|alt=Graph showing the growing number of laser-cooled molecules as a function of a year.|Directly laser cooled molecules.]]
Molecules are significantly more challenging to laser cool than atoms because molecules have vibrational and rotational degrees of freedom.  These extra degrees of freedom result in more energy levels that can be populated from excited state decays, requiring more lasers compared to atoms to address the more complex level structure.  Vibrational decays are particularly challenging because there are no symmetry rules that restrict the vibrational states that can be populated.

In 2010, at team at Yale led by [[David DeMille|Dave DeMille]] successfully laser-cooled a [[diatomic molecule]].<ref>{{cite journal |author1=E. S. Shuman |author2=J. F. Barry |author3=D. DeMille | title=Laser cooling of a diatomic molecule | journal=Nature | year=2010 | volume=467 |issue=7317 | pages=820–823 | doi=10.1038/nature09443 | pmid=20852614|arxiv = 1103.6004 |bibcode = 2010Natur.467..820S |s2cid=4430586 }}</ref> In 2016, a group at [[Max-Planck-Institut für Quantenoptik|MPQ]] successfully cooled [[formaldehyde]] to {{val|420|u=μK}} via optoelectric Sisyphus cooling.<ref>{{cite journal |last1=Prehn |first1=Alexander |last2=Ibrügger |first2=Martin |last3=Glöckner |first3=Rosa |last4=Rempe |first4=Gerhard |last5=Zeppenfeld |first5=Martin |title=Optoelectrical Cooling of Polar Molecules to Submillikelvin Temperatures |journal=Physical Review Letters |date=10 February 2016 |volume=116 |issue=6 |pages=063005 |doi=10.1103/PhysRevLett.116.063005 |pmid=26918988 |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.063005 |access-date=10 January 2024|arxiv=1511.09427 |bibcode=2016PhRvL.116f3005P }}</ref> In 2022, a group at Harvard successfully laser cooled and trapped CaOH to {{val|720|(40)|u=μK}} in a [[magneto-optical trap]].<ref>{{cite journal |author1=N. B. Vilas |author2= C. Hallas |author3=L. Anderegg |author4=P. Robichaud |author5=A. Winnicki |author6=D. Mitra |author7=J. M. Doyle | title=Magneto-optical trapping and sub-Doppler cooling of a polyatomic molecule | journal=Nature | year=2022 |volume= 606 |issue= 7912 |pages= 70–74 | doi=10.1038/s41586-022-04620-5 |pmid= 35650357 | arxiv = 2112.08349v1 |bibcode= 2022Natur.606...70V |s2cid= 245144894 }}</ref>