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.
In these lectures, we will study the bosonic theory of higher-spin gravity in four dimensions. After discussing the reasons for interest in the theory, we will focus on the equations of motion and their content. We will aim to construct the equations from the ground up in a motivated way. The logical order will differ somewhat from standard introductions. As preliminaries, we will discuss the geometry of spinors and twistors in (anti) de Sitter space, along with various viewpoints on free massless fields with arbitrary spin.
Using quantum control in foundational experiments allows new theoretical and experimental possibilities. We show how, e.g., quantum controlling devices reverse a temporal ordering in detection. We consider probing of wave–particle duality in quantum-controlled and the entanglement-assisted delayed-choice experiments. Then we discuss other situations where quantum control may be useful, and finally demonstrate how the techniques we developed are applied to the study of consistency of the classically reasonable requirements.
We review recent versions of the information paradox, framed in the context of the AdS/CFT correspondence. We describe how they can be resolved using "state dependent" bulk to boundary maps for the black hole interior in AdS/CFT. We argue that this feature is necessary not only for single sided black holes but also for the eternal black hole.
Astrophysical observations suggest that the majority of matter in the Universe is made up of novel Weakly Interacting Massive Particles (WIMPs). Such WIMPs are often predicted by extensions to the Standard Model. Efforts have been underway for more than two decades to detect WIMPs directly in detectors on earth. The challenge is great because of the small energies involved and the low interaction rates. The field has been driven by progress in detectors able to identify radioactive backgrounds.
Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental, particle nature of the dark matter.
In these lectures, we will study the bosonic theory of higher-spin gravity in four dimensions. After discussing the reasons for interest in the theory, we will focus on the equations of motion and their content. We will aim to construct the equations from the ground up in a motivated way. The logical order will differ somewhat from standard introductions. As preliminaries, we will discuss the geometry of spinors and twistors in (anti) de Sitter space, along with various viewpoints on free massless fields with arbitrary spin.
New developments in time-of-flight neutron spectroscopy allow a remarkably comprehensive determination of the full spin and phonon excitation spectrum in many materials. I will discuss these new techniques and show results from the "214" family of layered quantum magnets - which are also the La(2-x)Ba/Sr(x)CuO4 high Tc superconductors. We observe the expected highly dispersive spin excitations emanating from the "pi-pi" magnetic zone centres, as well as a host of optic and acoustic phonons, and roughly speaking, the spin and phonon excitations separate as a function of momentum.
Recently three-dimensional versions of honeycomb-lattice iridates, beta and gamma phases of Li2IrO3, have been discovered. It has been theoretically suggested that these hyperhoneycomb iridates may hold promise for the realization of the Kitaev spin liquid or the exactly solvable model for the elusive quantum spin liquid phase. Recent scattering experiments on these systems have, however, revealed highly non-trivial magnetic spiral phases.
Akin to liquid crystals, electronic nematic phases have been theorized and observed in several correlated materials, including cuprate and pnictide superconductors. I will discuss how electronic nematicity is observed in stripe-ordered cuprates using resonant x-ray scattering and how it relates to structural distortions and charge-density wave order.
In this talk, I will discuss some of the recent progress made on low energy effective field theories for non-Fermi liquids. Based on a dimensional regularization scheme, physical properties of various non-Fermi liquid states can be computed in controlled ways. I will emphasize novel features that arise due to the interplay between interaction and the presence of extensive gapless modes near Fermi surface. The examples include non-analytic expansion in coupling, emergent locality and UV/IR mixing.