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Q: Quantenoptik und Photonik

Q 52: Quanteninformation III

Q 52.4: Vortrag

Dienstag, 8. März 2005, 17:45–18:00, HU Audimax

Optimal entanglement and squeezing generation with noisy Gaussian channels — •Norbert Schuch, Michael M. Wolf, and J. Ignacio Cirac — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching

In quantum information processing with continuous variables, squeezing and entanglement are valuable resources which are hard to create, motivating the interest in efficient ways to generate them. Furthermore, channels creating these resources will in practice be noisy, i.e., non-unitary, making it even more demanding to create these quantities as quickly as possible.

We derive optimality results for the creation of both entanglement and squeezing with noisy Gaussian channels for various setups, where in general repeated applications of the channel are allowed and the channel is assisted by a set of additional operations which do not affect the resource. First, we consider the creation of squeezing with noisy maps supported by perfect passive transformations and explicitly derive optimal strategies. Second, we discuss the generation of entanglement between two Gaussian modes in two different scenarios: in one case, the set of available operations supplementing the channel is restricted to local passive operations, whereas in the second scenario all Gaussian local operations are permitted. We derive various results concerning the optimal creation of entanglement for both scenarios, and we also discuss the fundamental differences between both settings.