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Seminário do grupo de Óptica e Informação Quântica

Speaker: Ernesto F. Galvão

Title: Dimension and coherence witnesses from SWAP tests

Abstract:

The SWAP test is a simple quantum circuit that projects onto the symmetric subspace of two quantum systems. When applied to two separable states, it results in a direct estimation of the two-state overlap Tr(rho sigma). Using many such tests, we can gather information about many pairwise overlaps of N states. I’ll show how this relational information can be used to witness quantum coherence, i.e. guarantee that the states are not diagonal in any single basis. I’ll also show how these tests can be used as a Hilbert space dimension witness. Finally, I’ll briefly describe how to implement these tests using linear optics.