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.
Abstract The magic state model of quantum computation gives a recipe for universal quantum computation using perfect Clifford operations and repeat preparations of a noisy ancilla state. It is an open problem to determine which ancilla states enable universal quantum computation in this model. Here we show that for systems of odd dimension a necessary condition for a state to enable universal quantum computation is that it have negative representation in a particular quasi-probability representation which is a discrete analogue to the Wigner function.
Mass, a concept familiar to all of us, is also
one of the deepest
mysteries in nature. Almost all of the mass in the
visible universe,
you, me and any other stuff that we see around us, emerges from a
quantum field theory, called QCD, which has a completely negligible
microscopic mass content. How does QCD and the family of
gauge
theories it belongs to generate a mass?
This class of non-perturbative problems remained largely elusive despite much
I'll discuss solutions with Lifshitz scaling within
string supergravity for an arbitrary scaling component z. After showing how to
get exact Lifshitz spacetimes, I'll then look at more general solutions,
including black holes and flows between Lifshitz and adS spacetimes.
The axion provides a solution to the strong CP problem and is a cold dark matter candidate. I'll briefly review the limits on the axion from particle physics, stellar evolution and cosmology. The various constraints suggest that the axion mass is in the micro-eV to milli-eV range. In this window, axions contribute significantly to the energy density of the universe in the form of cold dark matter. It was recently found that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). As a result, it may be possible to distinguish axions from other forms of dark matter, suc
Over
the past several decades we have obtained increasingly precise data on the
distribution of galaxies in the Universe and on the distribution of primordial
perturbations via CMB measurements. This trend is likely to continue for
the foreseeable future. In this talk I will discuss some new things to do
with data from the CMB, galaxy surveys, and future 21-cm surveys look for new
physics in the early and late Universe. Topics will include cosmic
birefringence, new tests for parity violation, gravitational lensing,