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.
We investigate possible quantum spin liquid phases in the presence of a variety of spin-rotational-symmetry breaking perturbations. Projective symmetry group analysis on slave-particle representations is used to understand possible spin liquid phases on the Kagome lattice. The results of this analysis are used to make connections to the exiting and future experiments on Herbertsmithites. Applications to other systems are also discussed.
In two spatial dimensions, there is a good correspondence between TQFTs and topological phases of matter for spin systems. I will discuss this correspondence in one and three spatial dimensions for spin systems. If time permits, I will also discuss the situation for fermion systems.
I will discuss recent work on 3d Symmetry Protected Topological (SPT) phases of bosonic systems, and their implications for understanding the more exotic quantum spin liquid phases. First I will describe various characterizations of these 3d SPT phases, in particular their surface effective theories and (when applicable) bulk electromagnetic response. Next I will show how this understanding leads to several new insights into the theory of both 2d and 3d quantum spin liquids. Finally I will provide an explicit construction of several 3d SPT phases in a system of `coupled layers'.
The Pauli exclusion principle is a constraint on the
natural occupation numbers of fermionic states. It has been suspected for
decades, and only proved very recently, that there is a multitude of further
constraints on these numbers, generalizing the Pauli principle. Surprisingly,
these constraints are linear: they cut out a geometric object known as a
polytope. This is a beautiful mathematical result, but are there systems whose
physics is governed by these constraints?
We show that the recent AMS02
positron fraction measurement is perfectly consistent with a secondary origin for positrons, and does not require additional primary sources such as pulsars or dark matter. Within the secondary model the AMS02 data imply a cosmic ray propagation time in the
Galaxy of about one Myr and an average traversed interstellar matter density of about 1/cc at a rigidity of 300 GV. These results may hint that high energy cosmic rays are confined to a thin halo of scale height similar to the gaseous disk.
We reconstruct the experience of an infalling observer
using the AdS/CFT correspondence.
We write operators both outside and inside the black hole
in terms of CFT operators.
Our construction provides a natural realization of black
hole complementarity, and a way of preserving information without the need for
Based on her book, The Calculus Diaries, join, Jennifer Ouellette as she shows how calculus can be applied to everything from gas mileage, diet, the rides at Disneyland, surfing in Hawaii, shooting craps in Vegas and warding off zombies. Even the mathematically challenged, can-and-should learn the fundamentals of the universal language.
The Wigner-Araki-Yanase (WAY) theorem delineates
circumstances under which a class of quantum measurements is ruled out.
Specifically, it states that any observable (given as a self adjoint operator)
not commuting with an additive conserved quantity of a quantum system and
measuring apparatus combined admits no repeatable measurements. I'll review the
content of this theorem and present some new work which generalises and
strengthens the existing results.
Utilizing a variety and also
constraints offered by quantum and solid
state chemistry, we discuss
possibilities of unconventional quantum
magnetism and superconductivity
in doped 3 dimensional Mott insulators.
Some of the possibilities are
quantum spin liquid states having pseudo
fermi surface coexisting with
long range magnetic order, 3 dimensional
emergent gauge fields and
unconventional superconducting order parameter
It has been known for twenty years that a class of
two-dimensional gauge theories are intimately connected to toric geometry, as
well as to hypersurfaces or complete intersections in a toric varieties, and to
generalizations thereof. Under renormalization
group flow, the two-dimensional gauge theory flows to a conformal field theory
that describes string propagation on the associated geometry. This provides a connection between certain
quantities in the gauge theory and topological invariants of the associated