Hi all,
Next Wednesday, Pascal Neupert will talk about his master's thesis at 
4pm in HIT K52 (title and abstract below).  I propose we then continue 
regular research days in the usual Tuesday 5pm slot, the next one being 
in IFW the week after next.
See you next week,
Roger
Title: Securely Sharing Any Pure Quantum State
Abstract:
This talk will be about a particular cryptographic task between two 
mistrustful parties.  First, I will give a brief outline of the 
schematic of cryptographic protocols for two-party computation.  In 
particular quantum mechanics and the impossibility of faster-than-light 
signalling will be used to guarantee security.  I will also explain the 
security definitions associated with them.
In the second part I will introduce the task of secure state preparation 
(SSP), where the two parties, normally called Alice and Bob, want to 
share any prescribed pure quantum state, known to both of them.  I will 
describe a simple protocol which achieves this task with unconditional 
security.  I will then explain how this protocol can be extended such 
that Bob can choose a state to be shared from a prescribed (finite) set, 
while Alice is guaranteed only that the state came from this set and 
does not learn its identity.  At the end, I will briefly mention 
potential applications.