Hi all,
Tomorrow we have a visitor from downtown, Jansen Zhao Zhikuan from the CS
department, who will tell us about Causal limits on quantum communication.
See below for the abstract.
Best,
-joe
Title: Causal limit on quantum communication
Abstract:
The capacity of a channel is known to be equivalent to the highest rate at
which it can generate entanglement. Analogous to entanglement, the notion
of a causality measure characterizes the temporal aspect of quantum
correlations. Despite holding an equally fundamental role in physics,
temporal quantum correlations have yet to find their operational
significance in quantum communication. Here we uncover a connection between
quantum causality and channel capacity. We show the amount of temporal
correlations between two ends of the noisy quantum channel, as quantified
by a causality measure, implies a general upper bound on its channel
capacity. The expression of this new bound is simpler to evaluate than most
previously known bounds. We demonstrate the utility of this bound by
applying it to a class of shifted depolarizing channels, which results in
improvement over previously known bounds for this class of channels.