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Joined 2026-09-21 Message
Incoming links: Claude Cohen-Tannoudji
Nobel Prize in Physics in 1997 2026-10-18
Awarded in equal thirds to Steven Chu, Claude Cohen-Tannoudji and William D. Phillips for developing methods to cool and trap chemical atoms using lasers.[ref]
The Nobel Prize in Physics 1997 by Nobel Prize Outreach. Individual official 1997 summary: three one-third shares; methods for cooling and trapping atoms with laser light.
Polarization-gradient cooling Created 2026-10-14 Updated 2026-10-18
Polarization-gradient cooling uses spatial variation in electromagnetic polarization together with optical pumping between internal quantum states to cool moving chemical atoms.
Jean Dalibard and Claude Cohen-Tannoudji distinguish cooling by changing elliptical polarization from cooling by rotating linear polarization. The hill picture below concerns the former.[ref]
Sub-Doppler cooling discovery thermometry 2026-10-18
The 1988 experiment loaded sodium optical molasses from a slowed atomic beam. After stopping loading, a shutter extinguished the six cooling beams. Released atoms crossed a lower probe; a photomultiplier recorded fluorescence versus arrival time. Calculations integrated the measured initial cloud distribution and an assumed three-dimensional Maxwell-Boltzmann distribution, including gravity and detection geometry. The minimum was , versus the Doppler cooling limit.[ref]
Observation of Atoms Laser Cooled below the Doppler Limit by Paul D. Lett and others. pp. 169–170, preparation, TOF apparatus, Fig. 1 and uncertainty
Probe separation, probe intensity, cloud density and shutter timing were varied. Fountain-height, horizontal-spreading and release/recapture measurements also gave below-limit results. Geometry remained an uncertainty; agreement among complementary thermometers made a detector artifact less plausible. These measured released atoms, rather than an in-situ velocity distribution.[ref]
Observation of Atoms Laser Cooled below the Doppler Limit by Paul D. Lett and others. pp. 170–171, controls, four thermometers and release limitation
Steven Chu's account connects the explanation to optical pumping, Stark effect shifts and spatially changing electromagnetic polarization; Claude Cohen-Tannoudji's lecture separates this mechanism from subrecoil schemes. Their lectures and William D. Phillips's describe complementary experimental and theoretical routes.[ref]
The manipulation of neutral particles by Steven Chu. pp. 693–695, Fig. 6
[ref]Nobel Lecture: Manipulating atoms with photons by Claude Cohen-Tannoudji. pp. 710–713, §§II–III