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978-3-8439-0202-1, Reihe Physik
Continuous Loading of an Optical Dipole Trap
122 Seiten, Dissertation Universität Stuttgart (2011), Softcover, A5
In this thesis, I present a dissipative loading mechanism that allows to load a conservative potential trap continuously from a beam of particles. In a single step that involves optical pumping, the directed kinetic energy is removed and the particles end up in a trapped state. This scheme constitutes the central part of an alternative way to ultracold temperatures. Provided a slow beam can be produced, degeneracy may be reached without cooling on a closed cycling transition.
We demonstrate the loading scheme experimentally on a beam of ultracold chromium atoms. It is shown, that within less than 100 ms of loading, we reach an equilibrium with about 500000 trapped atoms. From this point, forced evaporative cooling leads to degeneracy within 4.2 s. The experimental results are compared to a theoretical description of the loading process with rate equations. On the basis of this, I analyze the temporal evolution of the trap parameters during the loading process. Furthermore, I discuss the current limitations to the scheme and suggest ways for a further improvement.