1 / 6

H. J. Metcalf, P. Straten, Laser Cooling and Trapping

H. J. Metcalf, P. Straten, Laser Cooling and Trapping. Beam deceleration with photon recoil. Absorb a photo to receive momentum kick Spontaneous emission is symmetric Random walk theory assumed Recoil limit. Raman transitions. A two-photon process: a simultaneous absorption

gabriella-consuela
Download Presentation

H. J. Metcalf, P. Straten, Laser Cooling and Trapping

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. H. J. Metcalf, P. Straten, Laser Cooling and Trapping

  2. Beam deceleration with photon recoil • Absorb a photo to receive momentum kick • Spontaneous emission is symmetric • Random walk theory assumed • Recoil limit

  3. Raman transitions • A two-photon process: a simultaneous absorption and a stimulated emission by an atom • Two counter-propagating beams • Resonant excitation condition • Linewidth determined by interaction time • At 600nm, pulse duration 0.6ms , equivalent to

  4. Raman cooling J. Foot, Atomic Physics

  5. Experimental demonstration by S. Chu et al. • Using Sodium with hyperfine ground states • Atoms were pre-cooled using beam deceleration magneto-optical trap, and 3D polarization gradient molasses. • Applied a sequence of Raman pulses with controlled linewidth and line shape. • Using Blackman pulse envelope to avoid unwanted off-resonant excitation • Achieve T=100nK, less than 1/10 recoil limit M. Kasevich, S. Chu, Laser cooling below a photon recoil with 3-level atoms, Phys. Rev. Lett. 69, 12 (1992)

  6. Fundamental limit • In theory one can arbitrarily narrow the linewidth • However it takes longer time for narrower linewidth, which limit the Raman cooling in practice.

More Related