Quantum Zeno paradox
In connection with the interpretation of quantum mechanics E. Schrödinger wrote in 1952: "... we never experiment with just one electron or atom ... In thought-experiments we sometimes assume that we do; this invariably entails ridiculous consequences ..." Taking advantage of modern trapping and cooling methods, repeated measurements on individual quantum systems have become possible, revealing the micro state of a system (as opposed to the ensemble average). In particular, the influence of a measurement on the time development of an individual quantum system can be studied. We have experimentally shown that the correlation between measurement apparatus and quantum system influences the dynamics of the quantum system, even without a direct (in a classical sense) interaction between the two. The information gained in a negative result measurement determines the evolution of the quantum system.