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PERIMETER INSTITUTE RECORDED SEMINAR ARCHIVE

PIRSA:C17020 - PI DayPODCAST Subscribe to podcast

PI Day

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Collection URL: http://pirsa.org/C17020


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PIRSA:17060017  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Relative entropy with a twist
Speaker(s): Matthew Beach
Abstract: Quantum relative entropy is a measure of the indistinguishability of two quantum states in the same Hilbert space. I will discuss the relative entropy between a state with periodic boundary conditions and one with twisted boundary conditions for a free 1+1 CFT with c=1. I will also highlight the u... read more
Date: 01/06/2017 - 9:30 am
Collection: PI Day

PIRSA:17060018  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum critical responses via holographic models and conformal perturbation theory
Speaker(s): Todd Sierens
Abstract: We investigate response functions near quantum critical points, allowing for finite temperature and a mild deformation by a relevant scalar. When the quantum critical point is described by a conformal field theory, we use conformal perturbation theory and holography to determine the two leading corr... read more
Date: 01/06/2017 - 9:50 am
Collection: PI Day

PIRSA:17060019  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum tunneling with a Lorentzian path integral
Speaker(s): Laura Sberna
Abstract: We describe the tunneling of a quantum mechanical particle with a Lorentzian (realtime) path integral. The analysis is made concrete by application to the inverted harmonic oscillator potential, where the path integral is known exactly. We apply Picard-Lefschetz theory to the time integral of the Fe... read more
Date: 01/06/2017 - 10:10 am
Collection: PI Day

PIRSA:17060020  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Rise of non-perturbative effects below the upper critical dimension
Speaker(s): Andres Schlief
Abstract: Extracting low energy universal data of quantum critical systems is a task whose difficulty increases with decreasing dimension. The increasing strength of quantum fluctuations can be tamed by using renormalization group (RG) schemes based on dimensional regularization close to the upper critical di... read more
Date: 01/06/2017 - 11:00 am
Collection: PI Day

PIRSA:17060021  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Topological field theories and gapped phases of matter
Speaker(s): Lakshya Bhardwaj
Abstract: I will introduce the idea that topological field theories describe the low-energy properties of gapped local quantum systems. This idea has proved fruitful in recent studies of gapped phases of matter.
Date: 01/06/2017 - 11:20 am
Collection: PI Day

PIRSA:17060022  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Gravity degrees of freedom on a null surface
Abstract: A canonical analysis for general relativity is performed on a null surface without fixing the diffeomorphism gauge, and the canonical pairs of configuration and momentum variables are derived. Next to the well-known spin-2 pair, also spin-1 and spin-0 pairs are identified. The boundary action for a ... read more
Date: 01/06/2017 - 11:40 am
Collection: PI Day

PIRSA:17060023  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Entanglement structure and UV regularization in cMERA
Abstract: We give an introduction to cMERA, a continuous tensor networks ansatz for ground states of QFTs. We also explore a particular feature of it: an intrinsic length scale that acts as an ultraviolet cutoff. We provide evidence for the existence of this cutoff based on the entanglement structure of a par... read more
Date: 01/06/2017 - 1:30 pm
Collection: PI Day

PIRSA:17050098  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Lorentzian quantum cosmology
Speaker(s): Job Feldbrugge
Abstract: Using Picard-Lefschetz theory we show that the Lorentzian path integral forms a good starting point for quantum cosmology which avoids the conformal factor problem present in Euclidean gravity. We study the Lorentzian path integral for a homogeneous and isotropic model with a positive cosmological c... read more
Date: 01/06/2017 - 1:50 pm
Collection: PI Day

PIRSA:17060024  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The holographic dual to general covariance
Speaker(s): Vasudev Shyam
Abstract: One of the defining features of holography is the geometerization of the renormalization group scale. This means that when a quantum field theory is holographically dual to a bulk gravity theory, then the direction normal to the boundary in the bulk (the `radial' direction) is to be interpreted as t... read more
Date: 01/06/2017 - 2:10 pm
Collection: PI Day

PIRSA:17060025  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Entanglement entropy of scalar fields in causal set theory
Abstract: Entanglement entropy is now widely accepted as having deep connections with quantum gravity. It is therefore desirable to understand it in the context of causal sets, especially since they provide in a natural and covariant manner the UV cutoff needed to render entanglement entropy finite. Defining ... read more
Date: 01/06/2017 - 3:00 pm
Collection: PI Day

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