Dear All,
The next QI Seminar is on Thursday, December 13 at 3:00 pm (IFW E44).
Speaker: Robert König, Institute for Quantum Information, California
Institute of Technology
Title: Sampling of min-entropy relative to quantum knowledge
Abstract:
The min-entropy H(X|E) quantifies the amount of secret key extractable
from a random variable X when an adversary holds a correlated system E.
Vadhan considered the case where X=(X_1,....X_n) is a bitstring and E is
a classical random variable. He showed that when selecting a
sufficiently large substring Z of X at random, the min-entropy-rate does
not decrease significantly, i.e., the fraction H(Z|E)/r, where r is the
length of Z, is lower bounded by H(X|E)/n. This result is a powerful
tool for the construction of so-called locally computable extractors
which have direct application to Maurer's bounded storage model. We
present an analogous result for the more general case where E is a
quantum system. It implies that Vadhan's sample-then-extract approach
provides security even against quantum adversaries.
This is joint work with Renato Renner.
Cheers,
Dejan