19 research outputs found
Security of EPR-based Quantum Cryptography against Incoherent Symmetric Attacks
We investigate a new strategy for incoherent eavesdropping in Ekert's
entanglement based quantum key distribution protocol. We show that under
certain assumptions of symmetry the effectiveness of this strategy reduces to
that of the original single qubit protocol of Bennett and Brassard
Communication Capacity of Quantum Computation
By considering quantum computation as a communication process, we relate its
efficiency to a communication capacity. This formalism allows us to rederive
lower bounds on the complexity of search algorithms. It also enables us to link
the mixedness of a quantum computer to its efficiency. We discuss the
implications of our results for quantum measurement.Comment: 4 pages, revte