14-Qubit Entanglement: Creation and Coherence
Thomas Monz, Philipp Claudius Schindler, Julio T. Barreiro, Michael Chwalla, Daniel Nigg, W. A. Coish, Maximilian Harlander, W. Hänsel, Markus Hennrich, R. Blatt · Physical Review Letters · 2011
We report the creation of Greenberger-Horne-Zeilinger states with up to 14 qubits. By investigating the coherence of up to 8 ions over time, we observe a decay proportional to the square of the number of qubits. The observed decay agrees with a theoretical model which assumes a system affected by correlated, Gaussian phase noise. This model holds for the majority of current experimental systems developed towards quantum computation and quantum metrology.