Search Talks

Search results from PIRSA

9901 - 9912 of 16777 Results

General Relativity for Cosmology - Lecture 22

Achim Kempf University of Waterloo

November 28, 2013

PIRSA:13110007
Divergences in Spinfoam Quantum Gravity

Aldo Riello Perimeter Institute for Theoretical Physics
November 28, 2013

PIRSA:13110063
General Relativity & Quantum Cosmology
Collisions in AdS and the thermalisation of heavy-ion collisions

Wilke van der Schee European Organization for Nuclear Research (CERN)
November 28, 2013

PIRSA:13110089
General Relativity & Quantum Cosmology
13/14 PSI - Condensed Matter - Lecture 14
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 28, 2013

PIRSA:13110044
13/14 PSI - Quantum Field Theory II - Lecture 14

Francois David CEA Saclay

November 28, 2013

PIRSA:13110025
The Secret to Engagement: Lessons from Video

Derek Muller

November 27, 2013

PIRSA:13110095
Homological Product Codes

Sergey Bravyi IBM (United States)
November 27, 2013

PIRSA:13110091
Quantum Physics
Insightful supersymmetry

Erich Poppitz University of Toronto
November 27, 2013

PIRSA:13110061
High Energy Physics
13/14 PSI - Condensed Matter - Lecture 13
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 27, 2013

PIRSA:13110043
13/14 PSI - Quantum Field Theory II - Lecture 13

Francois David CEA Saclay

November 27, 2013

PIRSA:13110024
General Relativity for Cosmology - Lecture 21

Achim Kempf University of Waterloo

November 26, 2013

PIRSA:13110003
Bounding the Elliptope of Quantum Correlations & Proving Separability in Mixed States

Elie Wolfe Perimeter Institute for Theoretical Physics
November 26, 2013

PIRSA:13110092
Quantum Physics

General Relativity for Cosmology - Lecture 22

Achim Kempf University of Waterloo

November 28, 2013

PIRSA:13110007
Divergences in Spinfoam Quantum Gravity

Aldo Riello Perimeter Institute for Theoretical Physics
November 28, 2013

PIRSA:13110063
General Relativity & Quantum Cosmology
The most relevant evidences in favour of the Lorentzian EPRL-FK spinfoam model come from its capibility of reproducing the expected semiclassical limit in the large spin regime. The main examples of this are the large spin limit of the vertex amplitude, later extended to arbitrary triangulations, and that of the spinfoam graviton propagator, which was calculated on the simplest possible two complex. These results are very promising. Nonetheless, their relevance may be endangered by the effects associated to radiative corrections. In this seminar, I will focus on the role played by the simplest diverging graph, the so called 'melon graph', which is known to play a fundamental role in tensorial group field theories. In particular, I will discuss its most divergent part and its geometrical interpretation. I will finally comment on the result, with particular attention to its physical consequences, especially in relation with the semiclassical limit of the spinfoam graviton propagator.
Collisions in AdS and the thermalisation of heavy-ion collisions

Wilke van der Schee European Organization for Nuclear Research (CERN)
November 28, 2013

PIRSA:13110089
General Relativity & Quantum Cosmology
The motivation of this seminar is to understand the thermalisation of heavy ion collisions using AdS/CFT. These collisions can be modelled as colliding planar gravitational shock waves. This gives rise to rich and interesting dynamics; wide shocks come to a full stop and expand hydrodynamically, as was previously found by Chesler and Yaffe. High energy collisions (corresponding to thin shocks) pass through each other, after which a plasma forms in the middle, within a proper time 1/T, with T the local temperature at that time. After this I will discuss recent results where we studied the influence of microscopic structure in the longitudinal direction of the shock waves, and thereby found a coherent regime. This has implications for both fluctuations in nucleus-nucleus collisions, and for recent proton-lead collisions at at LHC. The final part will cover a radially expanding calculation, where some simplifications allowed us to solve the model all the way till the final particle spectra, with an interesting comparison with experimental data.
13/14 PSI - Condensed Matter - Lecture 14
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 28, 2013

PIRSA:13110044
13/14 PSI - Quantum Field Theory II - Lecture 14

Francois David CEA Saclay

November 28, 2013

PIRSA:13110025
The Secret to Engagement: Lessons from Video

Derek Muller

November 27, 2013

PIRSA:13110095

Derek Muller from YouTube's Veritasium will present a webcast on Wednesday November 27, 2013 at 7pm EST from the Mike Lazaridis Theatre of Ideas at Perimeter Institute.Derek will discuss the question: Do videos really improve student learning? Derek’s PhD in physics education research suggests the answer may be no! In this one hour talk, he will share insights from his research as well as the incredible physics phenomena he has captured for his YouTube channel.Derek Muller created the popular YouTube channel Veritasium in January 2011. With almost 1 million subscribers, Derek’s 140 videos have received over 45 million views.
Homological Product Codes

Sergey Bravyi IBM (United States)
November 27, 2013

PIRSA:13110091
Quantum Physics
Quantum codes with low-weight stabilizers known as LDPC codes have been actively studied recently due to their potential applications in fault-tolerant quantum computing. However, all families of quantum LDPC codes known to this date suffer from a poor distance scaling limited by the square-root of the code length. This is in a sharp contrast with the classical case where good families of LDPC codes are known that combine constant encoding rate and linear distance. Here we propose the first family of good quantum codes with low-weight stabilizers. The new codes have a constant encoding rate, linear distance, and stabilizers acting on at most square root of n qubits, where n is the code length. For comparison, all previously known families of good quantum codes have stabilizers of linear weight. Our proof combines two techniques: randomized constructions of good quantum codes and the homological product operation from algebraic topology. We conjecture that similar methods can produce good stabilizer codes with stabilizer weight n^a for any a>0. Finally, we apply the homological product to construct new small codes with low-weight stabilizers. This is a joint work with Matthew Hastings.
Insightful supersymmetry

Erich Poppitz University of Toronto
November 27, 2013

PIRSA:13110061
High Energy Physics
It has recently been realized that some studies of supersymmetric gauge theories, when properly interpreted, lead to insights whose importance transcends supersymmetry. I will illustrate the insightful nature of supersymmetry by two examples having to do with the microscopic description of the thermal deconfinement transition, in non-supersymmetric pure Yang-Mills theory and in QCD with adjoint fermions. A host of strange ``topological" molecules will be seen to be the major players in the confinement-deconfinement dynamics. Interesting connections between topology, ``condensed-matter" gases of electric and magnetic charges, and attempts to interpret the divergent perturbation series will emerge. Much of the presentation will be aimed at non-experts.
13/14 PSI - Condensed Matter - Lecture 13
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 27, 2013

PIRSA:13110043
13/14 PSI - Quantum Field Theory II - Lecture 13

Francois David CEA Saclay

November 27, 2013

PIRSA:13110024
General Relativity for Cosmology - Lecture 21

Achim Kempf University of Waterloo

November 26, 2013

PIRSA:13110003
Bounding the Elliptope of Quantum Correlations & Proving Separability in Mixed States

Elie Wolfe Perimeter Institute for Theoretical Physics
November 26, 2013

PIRSA:13110092
Quantum Physics
We present a method for determining the maximum possible violation of any linear Bell inequality per quantum mechanics. Essentially this amounts to a constrained optimization problem for an observable’s eigenvalues, but the problem can be reformulated so as to be analytically tractable. This opens the door for an arbitrarily precise characterization of quantum correlations, including allowing for non-random marginal expectation values. Such a characterization is critical when contrasting QM to superficially similar general probabilistic theories. We use such marginal-involving quantum bounds to estimate the volume of all possible quantum statistics in the complete 8-dimensional probability space of the Bell-CHSH scenario, measured relative to both local hidden variable models as well as general no-signaling theories. See arXiv:1106.2169. Time permitting, we’ll also discuss how one might go about trying to prove that a given mixed state is, in fact, not entangled. (The converse problem of certifying non-zero entanglement has received extensive treatment already.) Instead of directly asking if any separable representation exists for the state, we suggest simply checking to see if it “fits” some particular known-separable form. We demonstrate how a surprisingly valuable sufficient separability criterion follows merely from considering a highly-generic separable form. The criterion we generate for diagonally-symmetric mixed states is apparently completely tight, necessary and sufficient. We use integration to quantify the “volume” of states captured by our criterion, and show that it is as large as the volume of states associated with the PPT criterion; this simultaneously proves our criterion to be necessary as well as the PPT criterion to be sufficient, on this family of states. The utility of a sufficient separability criterion is evidenced by categorically rejecting Dicke-model superradiance for entanglement generation schema. See arXiv:1307.5779.

Title	Date	Collection	Type	Info
General Relativity for Cosmology - Lecture 22	2013‑11‑28	General Relativity for Cosmology - 2013	Course	View details
Divergences in Spinfoam Quantum Gravity	2013‑11‑28	Quantum Gravity	Scientific Series	View details
Collisions in AdS and the thermalisation of heavy-ion collisions	2013‑11‑28	Strong Gravity	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 14	2013‑11‑28	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 14	2013‑11‑28	13/14 PSI - Quantum Field Theory II	Course	View details
The Secret to Engagement: Lessons from Video	2013‑11‑27	Public Lecture Series	Other	View details
Homological Product Codes	2013‑11‑27	Perimeter Institute Quantum Discussions	Scientific Series	View details
Insightful supersymmetry	2013‑11‑27	Colloquium	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 13	2013‑11‑27	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 13	2013‑11‑27	13/14 PSI - Quantum Field Theory II	Course	View details
General Relativity for Cosmology - Lecture 21	2013‑11‑26	General Relativity for Cosmology - 2013	Course	View details
Bounding the Elliptope of Quantum Correlations & Proving Separability in Mixed States	2013‑11‑26	Quantum Foundations	Scientific Series	View details

Supported by

Format results

General Relativity for Cosmology - Lecture 22

Divergences in Spinfoam Quantum Gravity

Collisions in AdS and the thermalisation of heavy-ion collisions

13/14 PSI - Condensed Matter - Lecture 14

13/14 PSI - Quantum Field Theory II - Lecture 14

The Secret to Engagement: Lessons from Video

Homological Product Codes

Insightful supersymmetry

13/14 PSI - Condensed Matter - Lecture 13

13/14 PSI - Quantum Field Theory II - Lecture 13

General Relativity for Cosmology - Lecture 21

Bounding the Elliptope of Quantum Correlations & Proving Separability in Mixed States

General Relativity for Cosmology - Lecture 22

Divergences in Spinfoam Quantum Gravity

Collisions in AdS and the thermalisation of heavy-ion collisions

13/14 PSI - Condensed Matter - Lecture 14

13/14 PSI - Quantum Field Theory II - Lecture 14

The Secret to Engagement: Lessons from Video

Homological Product Codes

Insightful supersymmetry

13/14 PSI - Condensed Matter - Lecture 13

13/14 PSI - Quantum Field Theory II - Lecture 13

General Relativity for Cosmology - Lecture 21

Bounding the Elliptope of Quantum Correlations & Proving Separability in Mixed States