COWATIN · Coherent wave guides for atom-interferometry

Final Activity Report Summary - COWATIN (Coherent waveguides for atom-interferometry)

The most important aim was to set up a state of the art cold atom laboratory on Crete. This was achieved very successfully. After some initial delay, the laboratory facilities ranked amongst the best in the world by the time of the project completion. We were able to attract a number of world class researchers to transfer their knowledge in atom physics. One of them was awarded a permanent position in the laboratory and set up his group, which was recognised via a Marie Curie excellence grant. As planned, by the end of the reporting period we were working on the final wave guide experiment. We published two papers on the theory of wave guided matter waves in the most reputable journal of the field, i.e. Physical Review Letters: 1. 'Spontaneous emergence of angular-momentum Josephson oscillations'. Josephson oscillations are one of the finest paradigms of quantum mechanics. Various types of Josephson oscillations exist, most of them involving a change of the spatial distribution of particles. In this paper we demonstrated, both analytically and numerically, that if two ring traps were brought close to each other atoms started to tunnel between the two. Due to the non-linearity, induced by atom-atom interactions in the individual rings, the initial symmetry of the system was broken and an angular-momentum Josephson oscillation occurred. Macroscopic currents appeared in the two rings which rotated in opposite directions. The total angular momentum remained conserved. The tunnelling then altered over time the direction of the current. The theoretical description of this was published in Physical Review Letters. We were also planning to test this at a later stage in our experiment. The paper was published as 'Spontaneous emergence of angular momentum Josephson oscillations in coupled annular Bose-Einstein condensates', by I. Lesanovsky and W. von Klitzing, published in Physical Review Letters 98:5 050401, 2007. 2. 'Time-averaged adiabatic potentials' was a theoretical treatment of time averaged adiabatic potentials (TAAP), which was the crucial part of the experiment. TAAP opened a new horizon for cold atom physics in that it allowed a novel trap shapes and coherent matter-wave guides. The paper was published as 'Time-averaged adiabatic potentials: Versatile matter-wave guides and atom traps, I. Lesanovsky and W. von Klitzing, Physical Review Letters 99:8 083001, 2007. One of the main challenges was the very complex control of radio-frequency and low frequency oscillating magnetic fields, which was finally achieved. Furthermore, the laser system was fully functional and the computer control almost finished. The vacuum system reached 10^-11 Torr. We had a working slow atom beam and a magneto-optical trap. One of the most exciting prospects was that early experiments were indicating that we had found a novel technique, which would enable us to image matter waves on a single atom level. This opened the perspective to perform quantum optical experiments with matter waves. However, since we were, as originally planned, still setting up the experiment, by the time of the project completion there were not very important experimental results available yet. Nevertheless, we achieved some very interesting technical advances in our laboratory, which would be published at later stages. These included: a novel design for a low Eddy current vacuum system 2. a novel magnetic coil design for very high direct current (DC) gradients 3. a novel tapered laser amplifier needing extremely low injection power.

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