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