Today on the archive
Wed Sep 6 08:53:53 EST 2006
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- Title: Large atom number Bose-Einstein condensate of sodium
- Authors: K.M.R. van der Stam, E.D. van Ooijen, R. Meppelink, J.M. Vogels, P. van der Straten
- Abstract: We describe the setup to create a large Bose-Einstein condensate containing more than 120x10^6 atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our experiments contains 2.0x10^10 atoms with a temperature of 320 microK and a density of about 1.0x10^11 atoms/cm^3. The sample is spin polarized in a high magnetic field, before the atoms are loaded in the magnetic trap. Spin polarizing in a high magnetic field results in an increase in the transfer efficiency by a factor of 2 compared to experiments without spin polarizing. In the magnetic trap the cloud is cooled to degeneracy in 50 s by evaporative cooling. To suppress the 3-body losses at the end of the evaporation the magnetic trap is decompressed in the axial direction.
- Comments: This experiment creates a BEC with roughly three times the number of atoms as the previous record, starting from a MOT that is two orders of magnitude smaller.
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- Title: Precise Control of Molecular Dynamics with a Femtosecond Frequency Comb - A Weak Field Route to Strong Field Coherent Control
- Authors: Avi Pe'er, Evgeny A. Shapiro, Matthew C. Stowe, Moshe Shapiro, Jun Ye
- Abstract: We present a general and highly efficient scheme for performing narrow-band Raman transitions between molecular vibrational levels using a coherent train of weak pump-dump pairs of shaped ultrashort pulses. The use of weak pulses permits an analytic description within the framework of coherent control in the perturbative regime, while coherent accumulation of many pulse pairs enables near unity transfer efficiency with a high spectral selectivity, thus forming a powerful combination of pump-dump control schemes and the precision of the frequency comb. The concept is presented analytically and its feasibility and robustness are verified by simulations of dynamics in Rb$_2$. We consider application of this concept to the formation of stable, deeply bound, ultracold molecules.
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