BEC – It‘s just like penguins

Bose-Einstein Condensate - Main People working on the experiment Publications related to the experiment Pictures of the setup

 

Memory Project

We are working towards implementing a multimode quantum memory in a cloud of ultracold atoms. The system is promising for high fidelity quantum state read-out, since it has a high optical depth. We want to explore how high an optical depth is permissible before collisional interaction between atoms or light diffraction seriously degrade the performance of a memory.
As a first building block to multimode storage we have implemented in-situ Faraday rotation imaging (see picture). We determine spatially resolved optical depths of condensates and thermal clouds to monitor multimode capability and diffraction effects.

 

Rayleigh Superradiance

In Rayleigh superradiance a cloud of atoms collectively scatters photons in the backward direction at a much faster rate than isolated atoms would do.We monitor the dynamics by recording both, the backward scattered photons and the recoiling atoms. Due to the very low momentum spread of the original cloud the recoiling atoms are spatially well seperated after a time of flight expansion (see picture). We studied the detuning dependence of this dynamic process and identified a regime of probe beam depletion at small detunings. The dynamics are understood with a matter-light coupled-wave model, which predicts the formation of a self-organized Bragg resonator structure inside the condensate.

Rayleigh superradiance and dynamic Bragg gratings in an end-pumped Bose-Einstein condensate
Hilliard, A., Kaminski, F., Le Targat, R., Olausson, C., Polzik, E.S. & Müller, J.H.
Physical Review A, 2008, Vol. 78(5), pp. 051403-+
doi:10.1103/PhysRevA.78.051403
arXiv:0810.5690

First BEC at Blegdamsvej 17!!

We created our first Rubidium 87 BEC in October 2006. The image shows the atomic cloud after time of flight for various evaporation cut frequencies. In our experiment atoms are laser-cooled in a double MOT system, then transferred into a QUIC type magnetic trap and further cooled to degeneracy by forced radio frequency evaporation. Our condensed clouds (h) are of prolate ellipsoidal shape and contain typically 106 atoms with Thomas-Fermi radii of 6/60µm at about 100nK temperature. 

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