Seminar
Tuesday, 15 December, 2009
Group seminar LMU: Quantum Walk in Position Space with Single Neutral Atoms
Tuesday, 15.12.2009 10 a.m. (s.t.) in H107, Fakultät für Physik LMU
Dr. Artur Widera, Arbeitsgruppe Laserphysik, Institut für Angewandte Physik, Universität Bonn
Recent advances in coherently controlling all degrees of freedom of single neutral atoms have paved the way for experiments that elucidate fundamental phenomena of quantum physics. Here, I will report on our observation of the quantum walk, the quantum analogue of the classical random walk.
I will show how single Caesium atoms can be spatially delocalized by entangling their internal degree of freedom with the atomic position. This ability directly enables the creation of spatial superposition states and multipath matter wave interference effects, such as the quantum walk. During this walk, a single atom is repeatedly delocalized over the sites of an optical lattice, and the probability to find an atom at a certain lattice site is dominated by matter wave interference of different partial wave packets of the atom. We observe the characteristic features of this quantum interference effect by fluorescence imaging of the atoms. Our result will allow shedding light, e.g., onto decoherence mechanisms affecting spatial superposition states.