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Video Library

Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres.  Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.  Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA)

PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.

Propagation of entanglement in strongly coupled systems from gravity

Wednesday May 08, 2013
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Thermodynamical Property of Entanglement Entropy for Excited States

Wednesday May 08, 2013
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We will point out that there is a universal thermodynamical property of entanglement entropy for excited states.  We will derive this by using the AdS/CFT correspondence in any dimension. We will also directly confirm this property from direct field theoretic calculations in two dimensions. We will define a new quantity called entanglement density by taking derivatives of entanglement entropy with respect to the shape of subsystem.

Impossible symmetry enriched topological phases in 2D and their realization on 3D surface

Tuesday May 07, 2013

In quantum systems with symmetry, the same topological phase can be enriched by symmetry in different ways, resulting in different symmetry transformations of the superselection sectors in the phase. However, not all symmetry transformations are allowed on the superselection sectors in topological phases in purely 2D systems. In this talk, I will discuss some examples of such symmetry enrichment of topological phases, which seem to be consistent with the fusion and braiding rules of the superselection sectors in the theory but are nonetheless impossible to realize in 2D.

Limitations on the psi-epistemic view of quantum states

Tuesday May 07, 2013
Speaker(s):

The
"psi-epistemic" view is that the quantum state does not represent a
state of the world, but a state of knowledge about the world.  It is
motivated, in part, by the observation of qualitative similarities between
characteristic properties of non-orthogonal quantum wavefunctions and between
overlapping classical probability distributions.  It might be suggested
that this gives a natural explanation for these properties, which seem puzzling
for the alternative "psi-ontic" view.  I will examine two such

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3D topological lattice models with topologically ordered surface states

Tuesday May 07, 2013
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I will discuss a family of solvable 3D lattice models that have a trivial" bulk, in which all excitations are confined, but exhibit topologically ordered surface states.  I will discuss perturbations to these models that can drive a phase transition in which some of these excitations become deconfined, driving the system into a phase with bulk topological order.

Field theory, Wave function, and Defects of Symmetry Protected Topological Phases

Tuesday May 07, 2013
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3D bosonic topological insulator and its exotic electromagnetic response

Tuesday May 07, 2013
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Recently, many new types of bosonic symmetry-protected topological phases, including bosonic topological insulators, were predicted using group cohomology theory.  The bosonic topological insulators have  both  U(1) symmetry (particle number conservation) and time-reversal symmetry, described by symmetry group $U(1)\rtimes Z_2^T$.  In this paper, we propose a projective construction of three-dimensional correlated gapped bosonic state with $U(1)\rtimes Z_2^T$ symmetry.  The gapped bosonic insulator is formed by eight kinds of charge-1 bosons.

Axiverse Cosmology and the Energy Scale of Inflation

Tuesday May 07, 2013
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Ultra-light axions (m_a
I will also present preliminary results of constraints to this model using up-to-date cosmological observations, which verify the above picture. The parameter space is interesting to explore due to a strongly mass dependent covariance matrix, motivating comparisons between Metropolis-Hastings and nested sampling. Finally I discuss fine-tuning and naturalness in these models.
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Majorana Ghosts: From topological superconductor to the origin of neutrino mass, three generations and their mass mixing

Tuesday May 07, 2013
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The existence of three generations of neutrinos and their mass mixing is a deep mystery of our universe. On the other hand, Majorana's elegant work on the real solution of Dirac equation predicted the existence of Majorana particles in our nature, unfortunately, these Majorana particles have never been observed. In this talk, I will begin with a simple 1D condensed matter model which realizes a T^2=-1 time reversal symmetry protected superconductors and then discuss the physical property of its boundary Majorana zero modes.

Fractionalizing Majorana fermions: non-abelian statistics on the edges of abelian quantum Hall states

Tuesday May 07, 2013
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We study the non-abelian statistics characterizing systems where counter-propagating gapless modes on the edges of fractional quantum Hall states are gapped by proximity-coupling to superconductors and ferromagnets. The most transparent example is that of a fractional quantum spin Hall state, in which electrons of one spin direction occupy a fractional quantum Hall state of $\nu= 1/m$, while electrons of the opposite spin occupy a similar state with $\nu = -1/m$. However, we also propose other examples of such systems, which are easier to realize experimentally.

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