[quantum-info] Talks and Visitors

[William Matthews]

If you notice something you feel is missing from this mail,
or have a correction, please inform the mailing list.

------ This week ------

-- Talks --

Tuesday, Nov 2nd 2010 1:30pm, U. of Guelph, SCIE1504,
Bei Zeng (IQC and University of Guelph)
Title: Quantum codes give counterexamples to the unique pre-image conjecture of the n-representability problem
Abstract: It is well known that the ground state energy of many-particle Hamiltonians involving only 2-body interactions can be obtained using constrained optimizations over density matrices which arise from reducing an N-body state. While determining which 2-body density matrices are "N-representable" is a computationally hard problem, all known extreme N-representable 2-body reduced density matrices arise from a unique N-body pre-image, satisfying a conjecture established in 1972. We present explicit counterexamples to this conjecture through giving Hamiltonians with 2-body interactions which have degenerate ground states that cannot be distinguished by any 2-body operator. We relate the existence of such counterexamples to quantum error correction codes and topologically ordered spin systems.

Thursday, Nov 4th 2010 12:00 noon, IQC, RAC1 Room 2009,
Seth Lloyd, MIT
Title: Sending a photon backwards in time
Abstract: Ever since Einstein, physicists have argued about whether time travel is consistent with the laws of physics, and, if so, how it might be accomplished. This talk presents a new theory of time travel based on quantum teleportation. Unlike previous theories, the theory can be tested experimentally. I report on an experimental realization of the `grandfather paradox': we send a photon a few billionths of a second backwards in time and have it try to `kill' its previous self.

-- Visitors --

Patrick Hayden (McGill University) will be visiting PI
November 1st through December 15th - Quantum Information
hosted by Neil Turok

Paolo Perinotti (Universita degli Studi di Pavia) will be visiting PI
November 4th through November 18th
hosted by Giulio Chiribella

------ Upcoming (next 4 weeks - not exhaustive!) ------

-- Talks --

Wednesday, Nov 8th 4:00pm, PI, Room 405,
Kristan Temme (University of Vienna)
"TBA" (Perimeter Institute Quantum Discussions)

Monday, Nov 15th 12:30 pm, IQC (RAC1) Room 2009
Patrick Hayden (McGill and Perimeter Institute)
"TBA"

Tuesday, Nov 16th 4:00pm, PI, Room 301
Marcin Pawlowski (Institute of Theoretical Physics and Astrophysics, Gdansk)
"What does information causality imply?"

Wednesday, Nov 24th 2:00 pm, PI, Room 405
Carl Bender
"Making sense of non-Hermitian Hamiltonians"

-- Visitors --

Kristan Temme (University of Vienna) will be visiting PI
November 6th through November 12th
hosted by Michele Mosca

Taylor Hughes (University of Illinois, Urbana-Champaign) will be visiting PI
November 8th through November 22nd
hosted by Alioscia Hamma

Giacomo Mauro D'Ariano (Universita degli Studi di Pavia) will be visiting PI
November 9th through December 2nd 
hosted by Giulio Chiribella

Marcin Pawlowski (University of Gdansk) will be visiting PI
November 14th through November 18th
hosted by Giulio Chiribella

Sergey Bravyi (IBM T. J. Watson Research Center) will be visiting PI
November 30th 2010 through December 2nd 2010
hosted by Lucien Hardy