Hello everyone,
As you may have guessed from the title of the email, we will have a
group seminar soon. More precisely on Monday (!), August 22, at 16:00 in
HIT K51. Sebastian Seehars will present his masters thesis.
Your outstanding seminar organizer,
--Frédéric
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Speaker: Sebastian Seehars
Title: Symmetric Extensions — Applications to Entanglement Detection and
Quantum Key Distribution
Date/Time/Place: Monday, August 22, 16:00, HIT K51
Abstract:
A bipartite quantum state is called symmetrically extendible if there
exists an extension to N Bobs such that tracing out all but any single
one of them results in the original quantum state. Symmetric extensions
are well known in the framework of entanglement detection as they give
rise to an efficient solution of the weak membership problem of
separability: Given an arbitrary bipartite quantum state, decide if it
is entangled or ε-close to the set of separable states.
In my talk, I will give a short introduction to the topic of symmetric
extensions and present new applications to quantum key distribution. It
turns out that we can find upper bounds to the secret key rate of a
state by considering its symmetric extendibility and the conditional
mutual information of its extensions. We apply this technique to get
improved upper bounds for the family of isotropic states.
The talk is based on results from my master thesis, supervised by
Matthias Christandl and Michael Walter.