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It is generally impossible to probe a quantum system without disturbing it. However, it is possible to exploit the back-action of quantum measurements and strong couplings to tailor and protect the coherent evolution of a quantum system. This is a profound and counterintuitive phenomenon known as quantum Zeno dynamics (QZD). Here we demonstrate QZD with a rubidium Bose-Einstein condensate in a five-level Hilbert space. We harness measurements and strong couplings to dynamically disconnect different groups of quantum states and constrain the atoms to coherently evolve inside a two-level subregion. In parallel to the foundational importance due to the realization of a dynamical superselection rule and the theory of quantum measurements, this is an important step forward in protecting and controlling quantum dynamics and, broadly speaking, quantum information processing. F. Schӓfer et al., S. Gherardini et al., |
Atoms few, damned but quick... Magnetic fields sources, RF antennas, optical structures, all integrated in a micro-chip with a Bose-Einstein condensate a few hundred microns from the surface: an "Atom chip". The benefits are higher trap frequencies, shorter evaporative time, better atom-field coupling plus a much (much) cheaper set-up. The goal of our experiment is to make the best use of Atom chips for quantum technological applications.