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# Vidéotheque

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.

## Towards local testability for quantum coding

Mercredi nov 27, 2019
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We introduce the hemicubic codes, a family of quantum codes obtained by associating qubits with the

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## A computationally universal phase of quantum matter

Mercredi nov 27, 2019
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We provide the first example of a symmetry protected quantum phase that has universal computational power. Throughout this phase, which lives in spatial dimension two, the ground state is a universal resource for measurement based quantum computation. Joint work with Cihan Okay, Dong-Sheng Wang, David T. Stephen, Hendrik Poulsen Nautrup; J-ref: Phys. Rev. Lett. 122, 090501

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## Fine-grained quantum supremacy and stabilizer rank

Mercredi nov 27, 2019
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It is known that several sub-universal quantum computing models cannot be classically simulated unless the polynomial-time
hierarchy collapses. However, these results exclude only polynomial-time classical simulations. In this talk, based on fine-grained
complexity conjectures, I show more fine-grained" quantum supremacy results that prohibit certain exponential-time classical simulations.
I also show the stabilizer rank conjecture under fine-grained complexity conjectures.

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## The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 9

Mercredi nov 27, 2019
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## Classical algorithms for quantum mean values

Mercredi nov 27, 2019
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Consider the task of estimating the expectation value of an n-qubit tensor product observable in the output state of a shallow quantum circuit. This task is a cornerstone of variational quantum algorithms for optimization, machine learning, and the simulation of quantum many-body systems. In this talk I will describe three special cases of this problem which are "easy" for classical computers. This is joint work with Sergey Bravyi and Ramis Movassagh.

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## PSI 2019/2020 - Quantum Field Theory II (David) - Lecture 10

Mercredi nov 27, 2019
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## Magic resource theories and classical simulation

Mardi nov 26, 2019
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I will review the stabiliser rank and associated pure state magic monotone, the extent, [Bravyi et. al 2019]. Then I will discuss several new magic monotones that can be regarded as a generalisation of the extent monotone to mixed states [Campbell et. al., in preparation]. My talk will outline several nice theorems we can prove about these monotones relate to each other and how they are related to the runtime of new classical simulation algorithms.

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## General Relativity for Cosmology - Lecture 22

Mardi nov 26, 2019
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## A post-quantum theory of classical gravity?

Mardi nov 26, 2019
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We consider a consistent theory of classical systems coupled to quantum ones. The dynamics is linear in the density matrix, completely positive and trace-preserving. We apply this to construct a theory of classical gravity coupled to quantum field theory. The theory doesn't suffer the pathologies of semi-classical gravity and reduces to Einstein's equations in the appropriate limit.

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## Variational Quantum Eigensolvers and contextuality

Mardi nov 26, 2019
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The variational quantum eigensolver (VQE) is the leading candidate for practical applications of Noisy Intermediate Scale Quantum (NISQ) devices. The method has been widely implemented on small NISQ machines in both superconducting and ion trap implementations. I will review progress to date and discuss two questions . Firstly, how quantum mechanical are small VQE demonstrations? We will analyze this question using strong measurement contextuality. Secondly, can VQE be implemented at the scale of devices capable of exhibiting quantum supremacy, around 50 qubits?

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## Lectures On-Demand

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