CONTACTS
 Coordinator
Diego Dalvit

Quantum Lunch Location:
TDivision Conference Room, TA3,
Building 123, Room 121

Quantum Institute: Visitor Schedule
The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA3, Building 123, Room 121. For more information, contact Diego Dalvit.
February 20, 2007
Monday, 12:30 PM
Jon Yard,
Caltech
Redistributing Quantum States
Abstract
Consider a pure quantum state with four parts and assume
that Alice holds two of them while Bob holds one. The last is
considered as an inaccessible "reference" system. For the situation
where many copies of the same state are present, I will characterize
the asymptotic resources which are necessary and sufficient for Alice
to give one of her parts to Bob, while preserving the purity of the
global state. For this, we allow Alice to send qubits to Bob; they
may also use preexisting entanglement. The required qubit cost gives
the first known operational interpretation of quantum conditional
mutual information on an arbitrary underlying state. The optimal
entanglement cost can be positive or negative, where in the latter
case, entanglement is generated by the process. Some intuitively
satisfying properties of our result include a timereversal symmetry,
together with a successive refinability property which is absent in
the classical theory. I will then show how this result organizes and
generalizes a large body of quantum informationtheoretic results of
recent years, such the quantum reverse Shannon and fully quantum
SlepianWolf theorems. I will conclude with some words on the quantum
method of types and some indications of future research directions.
