# Video Library

Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists 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 and 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.

Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.

## The "Zero Mode" in Kac Table: Revisiting the Ramond Sector of N=1 Superconformal Minimal Models

Tuesday May 21, 2019
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## Gravitational thermodynamics of causal diamonds

Tuesday May 21, 2019
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Black hole (more generally, horizon) thermodynamics is a window into quantum gravity. Can horizon thermodynamics---and ultimately quantum gravity---be quasi-localized? A special case is the static patch of de Sitter spacetime, known since the work of Gibbons and Hawking to admit a thermodynamic equilibrium interpretation. It turns out this interpretation requires that a negative temperature is assigned to the state. I'll discuss this example, and its generalization to all causal diamonds in maximally symmetric spacetimes.

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## Algebraic Braids and Geometric Representation Theory

Tuesday May 21, 2019
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In 2012, Maulik proved a conjecture of Oblomkov-Shende relating: (1) the Hilbert schemes of a plane curve (alternatively, its compactified Jacobian), (2) the HOMFLY polynomials of the links of its singularities. We recast his theorem from the viewpoint of representation theory. For a split semisimple group G with Weyl group W, we state a stronger conjecture relating two virtual modules over Lusztig's graded affine Hecke algebra,  constructed from: (1) fibers of a parabolic Hitchin map, (2) generalized Bott-Samelson spaces attached to conjugacy classes in the braid group of W.

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## Cosmological Collider Phenomenology: the Standard Model and Beyond

Tuesday May 21, 2019
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The n-point correlation functions (n>2) of primordial fluctuations, known as primordial non-Gaussianities, encode rich information about the physical degrees of freedom and their interactions at inflation scale, and can be viewed as signals from a cosmological collider with huge energy.

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## Mapping the baryonic universe: from reionization to present-day galaxies

Tuesday May 21, 2019
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The history of the baryonic (normal) matter in the universe is an excellent probe of the  formation of cosmic structures and the evolution of galaxies.  Over the last decade, considerable effort has gone into investigating the physics of baryonic material, particularly after the epoch of Cosmic Dawn: signalling the birth of the earliest stars and

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## Line of fixed points in a bosonic tensor model

Thursday May 16, 2019
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Tensor models exhibit a melonic large $N$ limit: this is a non trivial family of Feynman graphs that can be explicitly summed in many situations. In $d$ dimensions, they give rise to a new family of conformal field theories and provide interesting examples of the renormalization group flow from a free theory in the UV to a melonic large $N$ CFT in the IR.

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## New Developments In Gravitational Wave Data Analysis For Compact Binary Mergers

Thursday May 16, 2019
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Ground-based gravitational wave observatories have begun to uncover a large number of compact binary coalescences in the universe through gravitational wave signals. I will discuss novel and effective techniques we have developed recently to analyze the publicly available LIGO/Virgo bulk strain data from scratch. Built on simple ideas and easy to implement, those address the questions of template bank construction, signal processing, trigger ranking, and fast parameter estimation.

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## Good Approximate Quantum LDPC Codes from Spacetime Circuit Hamiltonians

Wednesday May 15, 2019
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We study approximate quantum low-density parity-check (QLDPC) codes, which are approximate quantum error-correcting codes specified as the ground space of a frustration-free local Hamiltonian, whose terms do not necessarily commute. Such codes generalize stabilizer QLDPC codes, which are exact quantum error-correcting codes with sparse, low-weight stabilizer generators (i.e. each stabilizer generator acts on a few qubits, and each qubit participates in a few stabilizer generators).

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## Einstein and Quantum Mechanics: It’s Not What You Think

Wednesday May 15, 2019
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Einstein is well known for his rejection of quantum mechanics in the form it emerged from the work of Heisenberg, Born and Schrodinger in 1926. Much less appreciated are the many seminal contributions he made to quantum theory prior to his final scientific verdict: that the theory was at best incomplete. In this talk I present an overview of Einstein’s many conceptual breakthroughs and place them in historical context. I argue that Einstein, much more than Planck, introduced the concept of quantization of energy in atomic mechanics.

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## A Gleason-type theorem for qubits based on mixtures of projective measurements

Tuesday May 14, 2019

We derive Born’s rule and the density-operator formalism for quantum systems with Hilbert spaces of finite dimension. Our extension of Gleason’s theorem only relies upon the consistent assignment of probabilities to the outcomes of projective measurements and their classical mixtures. This assumption is significantly weaker than those required for existing Gleason-type theorems valid in dimension two.

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