Hi all,
Tomorrow Sven Jandura will tell us about his master thesis with Ernest, entitled "De Finetti Theorems for Quantum Conditional Probability Distributions with Symmetry". See below for the abstract. We start at 2pm on zoom: https://ethz.zoom.us/j/362994444.
Best,
Joe
Abstract: In device independent quantum key distribution (DIQKD) Alice and Bob try to establish a shared secret key without trusting the devices used in key generation. The setup must therefore be treated as a black box and is mathematically described by a conditional probability distribution. Security proofs of DIQKD protocols can be simplified if the attacker can be restricted to attack each round in the key distribution process in an identical fashion (collective attacks). For many protocols such a reduction is available through the entropy accumulation theorem (EAT), but there are interesting protocols where the EAT is not applicable. In this presentation we introduce two de Finetti theorems that relate the properties of an arbitrary Clauser-Horne-Shimony-Holt (CHSH) symmetric quantum black box to a convex combination of iid quantum black boxes (de Finetti boxes). We further discuss how these theorems could be used in DIQKD security proofs, even if the EAT is not applicable, to impose restrictions on the attacker.