Abstract

We report on the demonstration of a very high flux of 6×10⁹ laser cooled chromium atoms per second in a magnetic guide. A high flux continuous source of cold atoms is one of the prerequisites for the realization of continuous atom lasers and for fast production of large quantum degenerate samples. The measured flux is comparable to the highest values (7×10⁹atoms/s) that have been observed by now for rubidium atoms [1]. In contrast to that experiment, the flux of chromium atoms is generated by the operation of a moving molasses / MOT within the magnetic field of the guide. The special electronic structure and the large magnetic moment of 6μ_B allows for an efficient continuous loading of laser cooled chromium atoms in such a configuration which has already been demonstrated in a magnetic trap. In our experiment, the atoms are laser-cooled into a moving frame whose velocity can be controlled by adjusting the relative detuning of the MOT/molasses beams. We investigate the optimum parameters for efficient loading and characterize the flux and temperature of the guided beam which is observed at a distance of ½ m from the MOT. To maximise the loading rate and flux, we have implemented a 2D cooling stage between the thermal atom source (T>1600°C) and the Zeeman slower. The increase in flux that is achieved by this technique exceeds one order of magnitude. The phase space density of the guided beam is on the order of 10⁻⁶ which is a very promising starting point for continuous loading of the guided atoms into an optical trapping potential.

© 2007 IEEE