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Quantum Information Processing

Dr. Charles H. Bennett of the IBM Watson Research Center delivered the first in a series of Kavli Institute-sponsored lectures on Thursday, April 21, at 4:00 pm, 700 Clark Hall. The lecture topic was "Quantum Information Processing." Dr. Bennett also offered a seminar on Wednesday, April 20, 2:30 pm, in 225 ILR Conference Center. A poster for the event is available in pdf format.

Quantum Information Processing (lecture)

When classical notions of information are generalized to obey the superposition principle of quantum physics, a simpler and grander theory of computation and communication emerges, extending the old theory somewhat as the complex numbers extend the real. Within this larger theory, classical information plays its usual robust role, while quantum information, in its fragility and privacy, may be compared to the information in a dream. We sketch the outlines of the enlarged theory, especially the pervasive role of entanglement in a variety of communications tasks that have no direct classical analog.

Assisted Capacities of Quantum Channels and the Reverse Shannon Theorem (seminar abstract)

Any process whereby a quantum system passes from a sender to a receiver, possibly interacting with some environment en route, may be regarded as a quantum channel. Unlike their classical analogs, quantum channels have multiple capacities depending on what one is trying to use them for (e.g. classical or quantum communication) and what auxiliary resources are brought into play. Among auxiliary resources, sender-receiver entanglement has a simplifying effect: in its presence all quantum channels become efficiently interconvertible (quantum reverse Shannon theorem). By contrast, classical feedback, or source-independent bidirectional classical side communication, which have no effect on a classical channel's single capacity, have a complicated effect on quantum channels, sometimes increasing both their quantum and capacities to values between the unassisted and the entanglement-assisted values. Joint work with Peter Shor, Igor Devetak, John Smolin and Andreas Winter.