Date: Thursday 16 November

Who: Miguel Aguado

Seminar type: Tutorial Seminar

Time: 12-1pm

Where: Interaction Room

Abstract:
After a review of `classical’ techniques from topology (homotopy, homology, cohomology), some applications to QI will be discussed. A model of Quantum Computation based on topological ideas (see M. Freedman et al., quant-ph/0001071, 0001108) will be presented.

Date: Friday 10th November

Who: Lluis Masanes

Seminar type: Research Seminar

Time: 12 Midday

Where: Interaction Room

Abstract:
What is quantum in quantum key distribution (QKD)? All non-signaling theories that predict the violation of a Bell inequality share some features with QM: monogamy of correlations, impossibility of perfect cloning, and potentiality for secret communication. This allows for proving the security of some QKD protocols by only assuming the impossibility of arbitrarily fast signaling. In this framework, all the analysis is made at the level of macroscopic events preparations/measurements), hence, Alice and Bob need not trust their devices as long as they produce the desired classical correlations.
Because our assumptions are weaker we give more power to the Eavesdropper, however, it is still possible to get a rate of one secret bit per singlet, as if we where assuming the whole of QM! As a side result, we obtain a classical exponential De Finetti theorem, which makes the i.i.d. assumption no longer necessary in most of classical information theory applications.