[quantum-info] Talks (one today!) and Visitors

[William Matthews]

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

-- Talks --

Monday, Dec 6th, 4:00pm, PI Room 405 (room changed from last mailing)
Oliver Buerschaper - Max-Planck-Institut für Quantenoptik
Title: Classifying Topological Order: Dualities and Hierarchies
Abstract: Topological order is a new kind of collective order which appears in two-dimensional quantum systems such as the fractional quantum Hall effect and brings about rather unusual particles: unlike bosons or fermions these anyons obey exotic statistics and can be exploited to perform quantum computation. Topological order also implies that quantum states at low energies exhibit a very subtle, yet intricate inner structure. Remarkably, both phenomena can be studied in relatively simple spin systems (like Kitaev's quantum double models and the ubiquitous toric code) which in fact capture the essential properties of entire topological phases of matter in many important cases. What is the relationship between these topological phases? Reviewing recent work I will explain how they arrange themselves in a landscape of dualities and hierarchies. In particular, I will focus on two aspects: first, a duality between electric and magnetic quasiparticles in generalized quantum double models and second, a hierarchy construction of quantum states which are related by the condensation of topological charges.

Tuesday, Dec 7th, 4:00 pm, PI, Room 301
Lucien Hardy - Perimeter Institute
Title: Turning pictures into calculations: the duotensor framework
Abstract: A picture can be used to represent an experiment. In this talk we will consider such pictures and show how to turn them into pictures representing calculations (in the style of Penrose's diagrammatic tensor notation). In particular, we will consider circuits described probabilistically. A circuit represents an experiment where we act on various systems with boxes, these boxes being connected by the passage of systems between them. We will make two assumptions concerning such  circuits. These two assumptions allow us to set up the duotensor framework (a duotensor is like a tensor except that each position is associated with two possible bases). We will see that quantum theory can be formulated in this framework. Each of the usual objects of quantum theory (states, measurements, transformations) are special cases of duotensors. The framework is motivated by the objective of providing a formulation of quantum theory which is local in the sense that, in doing a calculation pertaining to a particular region of spacetime, we need only use mathematical objects that pertain to this same region. This is, I argue, a prerequisite in a theory of quantum gravity. Reference for this talk: http://arxiv.org/abs/1005.5164

Wednesday, Dec 8th, 2:00 pm, PI, Room 405
David Cory - University of Waterloo
Title: From Quantum Parlor Tricks to Quantum Computing
Abstract: In RAC II at the Institute for Quantum Computing we are setting up a laboratory of test-beds for quantum information processing. I will describe the range of test-beds, what each offers for the development of quantum processors and where we are on the path towards a non-trivial quantum processor.

-- Visitors --

Jacob Biamonte (Oxford) is visiting IQC
until December 7th 2010
hosted by Michele Mosca

Oliver Buerschaper (Max-Planck-Institut für Quantenoptik)
until December 11th 2010
hosted by Michele Mosca

Patrick Hayden (McGill University) is visiting PI
until December 15th
hosted by Neil Turok

Thomas Vidick (Berkeley) will be visiting IQC
from December 12th - Dec. 17th 2010
hosted by Ashwin Nayak

Lianao Wu (University of the Basque Country) is visiting PI
until December 18th 2010 
hosted by Daniel Gottesman

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

-- Talks --

Tuesday 14th December 2010
Quantum Foundations
"Limits on non-local correlations from the structure of the local state space"
with Peter Janotta
at 04:00 pm in 301

-- Visitors --