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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.

## 12/13 PSI - Explorations in Condensed Matter Lecture 15

Friday Apr 26, 2013
Speaker(s):

## Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Thursday Apr 25, 2013
Speaker(s):

The physics of iridium-based 5d transition metal oxides has attracted significant interest due to the potential for exotic magnetic and electronic ground states driven by strong spin-orbit coupling effects. Among the most extensively studied iridates is the layered perovskite Sr2IrO4, which was recently proposed as the first experimental realization of a novel Jeff=1/2 spin-orbital Mott insulating state.

## Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

Thursday Apr 25, 2013
Speaker(s):

In this talk I will briefly review the polaron physics, which has helped theorists to conceive the BCS theory of conventional superconductors as well as experimentalists to discover high temperature superconductors in the cuprates. Specifically I will talk about how charge carriers obtain their
masses from coupling to the phonon field in one, two, three or higher dimensions. More recently, there is increasing interest in topological insulators where a gap can be opened which may suggest new version of Higgs mechanism in condensed matter.

## Tensor Networks: an Overview

Thursday Apr 25, 2013
Speaker(s):

Tensor network algorithms provide highly competitive tools for analyzing ground state properties of quantum lattice models in one and two spatial dimensions. The most notable examples involve matrix product states, projected entangled pair states and multiscale entanglement renormalization ansatz. The key underlying idea of all the approaches is to decompose a quantum many-body state into a carefully chosen network of tensors.
In this talk I will give an introduction to the subject and show how tensor networks can be used to characterize topological order.

## New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Thursday Apr 25, 2013
Speaker(s):

The ground state of the candidate spin liquid pyrochlore magnet Tb2Ti2O7 (TTO) has been long debated. Despite theoretical expectations of magnetic order below ~1K based on classical Ising-like Tb3+ spins, earlier muSR and neutron scattering experiments showed no long range order down to 50mK. This motivated two theoretical scenarios to account for the apparently disordered ground state: a quantum spin ice scenario and a non-magnetic singlet ground state.

## Absence of Pauling's Residual Entropy in Dy2Ti2O

Thursday Apr 25, 2013
Speaker(s):

The discovery of the spin-ice phase in Dy2Ti2O7 numbers among the most significant findings in magnetic materials in over a decade. The spin-ice model is based on an elegant analogy to Pauling’s model of geometrical frustration in water ice, and predicts the same residual entropy, as confirmed by numerous measurements. Melko, den Hertog and Gingras, with numerical work using a loop algorithm to speed up equilibration times, were able to determine an ordering for this system. This had not been seen experimentally observed by several groups.

## Loop quantization of a weak-coupling limit of Euclidean gravity

Thursday Apr 25, 2013
Speaker(s):

I will describe recent work in collaboration with Adam
certain $G_{\mathrm{N}}\rightarrow 0$ limit of Euclidean gravity, introduced by
Smolin. The model allows one to test various quantization choices one is faced
with in loop quantum gravity, but in a simplified setting.  The main results are the construction of
finite-triangulation Hamiltonian and diffeomorphism constraint operators whose
continuum limits can be evaluated in a precise sense, such that the quantum

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## Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Thursday Apr 25, 2013
Speaker(s):

The last few years have seen new opportunities for
constraining the physics of neutron star interiors. I will first discuss the
current state of neutron star radius measurements and then go on to discuss
thermal tomography as a probe of the nuclear, magnetic, and transport
properties of neutron star crusts. In each case, I will emphasize the
astrophysics that must be understood to make reliable inferences about the
properties of dense matter from observations of neutron stars.

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## 12/13 PSI - Explorations in String Theory Lecture 14

Thursday Apr 25, 2013
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## The Quantum von Neumann Architecture and the Future of Quantum Computing with Superconducting Circuits

Thursday Apr 25, 2013
Speaker(s):

Superconducting quantum circuits have made significant advances over the past decade, allowing more complex and integrated circuits that perform with good fidelity. We have recently implemented a machine comprising seven quantum channels, with three superconducting resonators, two phase qubits, and two zeroing registers. I will explain the design and operation of this machine, first showing how a single microwave photon |1> can be prepared in one resonator and coherently transferred between the three resonators [1].

## RECENT PUBLIC LECTURE

### Dangerous Curves: How I Learned To Stop Worrying and Love the Calculus

Speaker: Jennifer Ouellette