>VITAE:
Paolo Zanardi got his PhD in 1995 in the II University of Rome working on strongly correlated fermion systems. Since 1996 he got interested in Quantum Information and computation and joined the newly born QIP research Group at the ISI Foundation in Torino. Ever since then he has been active in the field working on a diverse bunch topics e.g., decoherence control/avoidance, geometrical quantum computing, QIP implementation with solid state systems, entanglement in interacting systems of spins and indistinguishable particles. Paolo Zanardi is currently coordinating the EU IST project TOPQIP on topological quantum information processing.

Quantum entaglement is widely believed to be the unique quantum resource at the basis of the speeups achievable by processing information in a quantum fashion. The very definition of this resource assumes the partition of a system into subsystems i.e., a tensor product structure at the Hilbert state-space level. Operationally, this partition is dictated by the set interactions and measurements physically accessible by an observer. The emergence of a multi-partite tensor product structure of the state-space, and so the notion of quantum entanglement, are then relative and observer-induced.
I will introduce a general, operationally motivated, framework, based on operator-algebras, aimed to formalize this ideas.
I will introduce the notion of virtual quantum subystem and discuss several cases relevant to quantum information processing as well as to decoherence avoidance.