Editing Laser cooling (section)

=== Laser cooling proposals ===
The introduction of [[laser]]s in atomic physics experiments was the precursor to the laser cooling proposals in the mid 1970s. Laser cooling was proposed separately in 1975 by two different research groups: [[Theodor W. Hänsch|Hänsch]] and [[Arthur Leonard Schawlow|Schawlow]],<ref name="Hänsch1975">
{{cite journal |last1=Hänsch |first1=T. W. |last2=Schawlow |first2=A. L. |author1-link= Theodor W. Hänsch|author2-link=Arthur Leonard Schawlow|title=Cooling of gases by laser radiation |journal=Optics Communications |date=January 1975 |volume=13 |issue=1 |pages=68–69 |doi=10.1016/0030-4018(75)90159-5|doi-access=free |bibcode=1975OptCo..13...68H }}</ref> and [[David Wineland|Wineland]] and [[Hans Georg Dehmelt|Dehmelt]].<ref>{{cite journal |last1=Wineland |first1=David |last2=Dehmelt |first2=Hans |author1-link=David Wineland|author2-link=Hans Georg Dehmelt|title=Proposed 10<sup>14</sup> {{nowrap|∆''ν'' < ''ν''}} laser fluorescence spectroscopy on T1<sup>+</sup> mono-ion oscillator III  |journal=Bulletin of the American Physical Society |date=January 1, 1975 |volume=20 |issue=4 |page=637}}</ref> Both proposals outlined the simplest laser cooling process, known as [[Doppler cooling]], where laser light tuned below an atom's resonant frequency is preferentially absorbed by atoms moving towards the laser and after absorption a photon is emitted in a random direction.  This process is repeated many times and in a configuration with counterpropagating laser cooling light the velocity distribution of the atoms is reduced.<ref name=":0">
{{cite journal|last=Phillips|first=William D.|title=Nobel Lecture: Laser cooling and trapping of neutral atoms|journal=Reviews of Modern Physics|volume=70|issue=3|pages=721–741|doi=10.1103/revmodphys.70.721|bibcode=1998RvMP...70..721P|year=1998|doi-access=free}}</ref> 

In 1977 [[Arthur Ashkin|Ashkin]] submitted a paper which describes how Doppler cooling could be used to provide the necessary damping to load atoms into an optical trap.<ref>{{cite journal |last1=Ashkin |first1=A. |author-link=Arthur Ashkin|title=Trapping of Atoms by Resonance Radiation Pressure |journal=Physical Review Letters |date=20 March 1978 |volume=40 |issue=12 |pages=729–732 |doi=10.1103/PhysRevLett.40.729|bibcode=1978PhRvL..40..729A }}</ref>  In this work he emphasized how this could allow for long [[Spectroscopy|spectroscopic]] measurements which would increase precision because the atoms would be held in place.  He also discussed overlapping [[Optical tweezers|optical traps]] to study interactions between different atoms.