SIGNIFICANT EVENTS - SCIENCE EVENTS
01/10/03

Ketterle Group at MIT Publishes Research Results

Several articles describing the research by PI Wolfgang Ketterle's group at MIT have been recently published. The article "Imprinting vortices in a Bose-Einstein condensate using topological phases" by A.E. Leanhardt, A. Göerlitz, A.P. Chikkatur, D. Kielpinski, Y. Shin, D.E. Pritchard, and W. Ketterle appeared in Physical Review Letters (Phys. Rev. Lett. 89,190403 (2002)). The article describes a sodium condensates held in a Ioffe-Pritchard magnetic trap that were transformed from a non-rotating state to one with quantized circulation by adiabatically inverting the magnetic bias field along the trap axis. Using surface wave spectroscopy, the axial angular momentum per particle of the vortex states was found to be consistent with 2 or 4, depending on the hyperfine state of the condensate.

Also, the article "A Continuous Source of Bose-Einstein Condensed Atoms" appeared in Science Magazine (Science 296, 2193-2195 (2002)) authored by A. P. Chikkatur, Y. Shin, A. E. Leanhardt, D. Kielpinski, E. Tsikata, T. L. Gustavson, D. E. Pritchard, and W. Ketterle. The authors state, "All atom lasers to date have operated in a pulsed mode. Coherent streams of atoms were generated until a single condensate was completely depleted. Using our continuous BEC source, one could implement CW-outcoupling and create a truly continuous atom laser."

As well, this group published in Physical Review Letters the article titled "Generation of macroscopic pair-correlated atomic beams by four-wave mixing in Bose-Einstein condensates" (Phys. Rev. Lett. 89, 020401 (2002), authors J.M. Vogels, K. Xu, and W. Ketterle). Quoting from the article: "In a gaseous Bose-Einstein condensate (BEC), all the atoms occupy the ground state of the system. Once BEC has been achieved, the initial well-defined quantum state can be transformed into other more complex states by manipulating it with magnetic and optical fields... By colliding two Bose-Einstein condensates, we have observed strong bosonic stimulation of the elastic scattering process. When a weak input beam was applied as a seed, it was amplified by a factor of 20. This large gain atomic four-wave mixing resulted in the generation of two macroscopically occupied pair-correlated atomic beams."