Atom cooling / trapping and quantum optics


 

Doppler laser atom cooling laser atom trapping MOT

Simplified principle of Doppler laser cooling:

(1) A stationary atom sees the laser neither red- nor blue-shifted and does not absorb the photon.

(2) An atom moving away from the laser sees it red-shifted and does not absorb the photon.

(3.1) An atom moving towards the laser sees it blue-shifted and absorbs the photon, slowing the atom.

(3.2) The photon excites the atom, moving an electron to a higher quantum state.

(3.3) The atom re-emits a photon. As its direction is random, there is no net change in momentum over many atoms.

Author:

Cmglee

   

 

Atom cooling: Users want to match an atom ray è need a single frequency linewidth and a precise control of the central wavelength. Low noise, power stability and pointing stability are also important specifications. Atoms cooling is a much more demanding application than atoms trapping.

Azur Light Systems offers tunable seeders (thermal & piezo locked) to seed one or multiple optical amplifiers.

Atom trapping / Optical tweezing: The aim is to generate an optical trap for atoms. This trap will cool down the atoms but the central wavelength and the linewidth of the radiation don’t matter. Generally a wavelength anywhere in the infrared region is a good option (1064nm for instance). Low noise, power stability and pointing stability are the most important parameters to obtain the best results.

Quantum optic / Interferometry: High precision interferometry and fundamental quantum optics now enable the study of previously unobserved phenomena such as gravitational waves. The observation of these effects is only possible with an ultra-stable low noise laser. Parameters of interest are low noise level, spectral width and stability.

a.      ALS technological advantages

  • Thanks to the MOPA configuration, it is possible to choose a particular wavelength or a tunable seeder to match the atom rays of interest.
  • ALS-IR lasers benefit from one the best frequency stability on the market (< 50 MHz over 8h).
  • The fiber laser technology and the cooler-less laser head allows an excellent pointing and spatial mode stability. It also avoid any vibration of the experimental table which is essential.
  • Power stability is also really important because a change in power will affect the efficiency of the atom trap.
  • Noise level matter for atom cooling/trapping application as well as for interferometry application. That is why most users choose our single frequency version to benefit of its ultra-low noise level even if they don’t always need a single frequency linewidth.

b.      Lasers versions

ALS-IR - from 5W to 50W@1064nm / 1040nm / 1050nm / 1030nm – single frequency

ALS-VISIBLE –1 W to 10W @488nm, 515nm or 532nm – single frequency

 

Web Links:

https://en.wikipedia.org/wiki/Magneto-optical_trap
https://en.wikipedia.org/wiki/Laser_cooling
http://www.mpq.mpg.de/5275582/PR_16_01_04_en.pdf
https://syrte.obspm.fr/spip/science/fmo/horloges-compactes-cpt-et-horace/?lang=en
https://syrte.obspm.fr/spip/?lang=en
http://www.phys.ens.fr/~cct/articles/dans-livres/Jean1.pdf 
http://www.lkb.ens.fr/-Condensats-de-Bose-Einstein-