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Q: Quantenoptik und Photonik

Q 52: Quanteninformation III

Q 52.2: Vortrag

Dienstag, 8. März 2005, 17:15–17:30, HU Audimax

Standard forms of noisy evolutions via depolarization — •Marc Hein¹, Wolfgang Dür¹, and Hans Jürgen Briegel^1,2 — ¹Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Österreich — ²Institut für Quantenoptik und Quanteninformation der Österreichischen Akademie der Wissenschaften, Innsbruck, Österreich

We consider noisy, non-local unitary operations or interactions, i.e. the corresponding evolutions are described by completely positive maps or master equations of Lindbladt form. We show that by random local operations the maps or Liovillians can be depolarized to a standard form with a reduced number of parameters describing the noise process in such a way that the noiseless (Hamiltonian) part of the evolution is not altered. A further reduction of the parameters, in many cases even to a single one (i.e. global white noise), is possible by tailoring the evolutions and increasing the amount of noise. The resulting standard forms may be used to compute lower bounds on channel capacities and the lifetime of entangled states. Moreover these standard forms might be useful to derive error thresholds for entanglement purification and quantum computation which are valid for a more general class of noise processes.