Editing Matter wave (section)

==== Atoms ====
Interference of atom matter waves was first observed by [[Immanuel Estermann]] and [[Otto Stern]] in 1930, when a Na beam was diffracted off a surface of NaCl.<ref>{{cite journal | last1 = Estermann | first1 = I. | author-link2 = Otto Stern | last2 = Stern | first2 = Otto | year = 1930 | title =  Beugung von Molekularstrahlen| journal = Z. Phys. | volume = 61 | issue = 1–2| page = 95 | doi=10.1007/bf01340293|bibcode = 1930ZPhy...61...95E | s2cid = 121757478 }}</ref> The short de Broglie wavelength of atoms prevented progress for many years until two technological breakthroughs revived interest: [[microlithography]] allowing precise small devices and [[laser cooling]] allowing atoms to be slowed, increasing their de Broglie wavelength.<ref name="Adams Sigel Mlynek 1994 pp. 143–210">{{cite journal | last1=Adams | first1=C.S | last2=Sigel | first2=M | last3=Mlynek | first3=J | title=Atom optics | journal=Physics Reports | publisher=Elsevier BV | volume=240 | issue=3 | year=1994 | issn=0370-1573 | doi=10.1016/0370-1573(94)90066-3 | pages=143–210| bibcode=1994PhR...240..143A | doi-access=free }}</ref> The double-slit experiment on atoms was performed in 1991.<ref>{{Cite journal |last1=Carnal |first1=O. |last2=Mlynek |first2=J. |date=1991-05-27 |title=Young's double-slit experiment with atoms: A simple atom interferometer |url=https://pubmed.ncbi.nlm.nih.gov/10043591/ |journal=Physical Review Letters |volume=66 |issue=21 |pages=2689–2692 |doi=10.1103/PhysRevLett.66.2689 |issn=1079-7114 |pmid=10043591|bibcode=1991PhRvL..66.2689C }}</ref>

Advances in [[laser cooling]] allowed cooling of neutral atoms down to nanokelvin temperatures. At these temperatures, the de Broglie wavelengths come into the micrometre range. Using [[Bragg's law|Bragg diffraction]] of atoms and a Ramsey interferometry technique, the de Broglie wavelength of cold [[sodium]] atoms was explicitly measured and found to be consistent with the temperature measured by a different method.<ref name="Cla">
{{cite journal
 |author=Pierre Cladé
 |author2=Changhyun Ryu |author3=Anand Ramanathan |author4=Kristian Helmerson |author5=William D. Phillips
 |title=Observation of a 2D Bose Gas: From thermal to quasi-condensate to superfluid
 |date=2008
 |arxiv=0805.3519
 |doi=10.1103/PhysRevLett.102.170401
 |pmid=19518764 |volume=102
 |issue=17
 |page=170401 |journal=Physical Review Letters
 |bibcode=2009PhRvL.102q0401C
 |s2cid=19465661
}}</ref>