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Q: Fachverband Quantenoptik und Photonik

Q 25: Quanteninformation (Verschränkung und Dekohärenz II)

Q 25.6: Vortrag

Dienstag, 20. März 2007, 15:30–15:45, 5L

Quantum Walks with Decoherence — •Annette Maria Gattner and Reinhard Werner — Institut für mathematische Physik, TU Braunschweig, www.imaph.tu-bs.de

The transition from classical to quantum walks implies the introduction of an additional coin degree of freedom to obtain unitary but nontrivial quantum walks. This unitarity can be destroyed by decoherence, e.g., the use of a different quantum coin with a certain probability. The effects of such kinds of decoherence as well as errors in the position degree of freedom have already been studied numerically by several groups. The study of decoherence is especially important with regard to the experimental realization of quantum walks and the occurring imperfections.

When decoherence is allowed, one can consider translationally invariant local discrete time dynamics without any additional coin degree of freedom. We present the possible decoherence maps under such conditions and determine their probability distribution for large times. These results are extended to the quantum walk with a coin degree of freedom.