Talks

9853 - 9864 of 16754 Results

Dimensional reduction in the sky

November 21, 2013

PIRSA:13110059

Quantum Gravity
Charged particle motion in magnetized black holes

Valeri Frolov University of Alberta

November 21, 2013

PIRSA:13110066

Strong Gravity
13/14 PSI - Condensed Matter - Lecture 9

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 21, 2013

PIRSA:13110037
13/14 PSI - Quantum Field Theory II - Lecture 9

Francois David CEA Saclay

November 21, 2013

PIRSA:13110018
Quantum Adversary (Upper) Bound

Shelby Kimmel Massachusetts Institute of Technology (MIT)

November 20, 2013

PIRSA:13110090

Quantum Information
Light and matter: towards macroscopic quantum systems

Jacob Taylor Office of Science and Technology Policy

November 20, 2013

PIRSA:13110060

Quantum Information
13/14 PSI - Condensed Matter - Lecture 8

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 20, 2013

PIRSA:13110036
13/14 PSI - Quantum Field Theory II - Lecture 8

Francois David CEA Saclay

November 20, 2013

PIRSA:13110017
General Relativity for Cosmology - Lecture 18

Achim Kempf University of Waterloo

November 19, 2013

PIRSA:13110005
The Amplitude Mode in Condensed Matter : Higgs Hunting on a Budget

Daniel Arovas University of California, San Diego

November 19, 2013

PIRSA:13110054

Condensed Matter
New Light Species and the CMB - Joint Cosmology/Particle Physics Seminar

Christopher Brust

November 19, 2013

PIRSA:13110051

Particle Physics
13/14 PSI - Condensed Matter - Lecture 7

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 19, 2013

PIRSA:13110035

Dimensional reduction in the sky

November 21, 2013

PIRSA:13110059

Quantum Gravity

In several approaches to quantum-gravity, the spectral dimension of spacetime runs from the standard value of 4 in the infrared (IR) to a smaller value in the ultraviolet (UV). Describing this running in terms of deformed dispersion relations, I show that a striking cosmological implication is that that UV behavior leading to 2 spectral dimensions results in an exactly scale-invariant spectrum of vacuum scalar and tensor fluctuations. I discuss scenarios that break exact scale-invariance and show that the tensor to scalar ratio is fixed by the UV ratio between the speed of gravity and the speed of light. Cosmological perturbations in this framework display a wavelength-dependent speed of light, but by transforming to a suitable "rainbow frame" this feature can be removed, at the expense of modifying gravity. In particular it turns out that the following concepts are closely connected: scale-invariance of vacuum fluctuations, conformal invariance of the gravitational coupling, UV reduction to spectral dimension 2 in position space and UV reduction to Hausdorff dimension 2 in energy-momentum space.
Charged particle motion in magnetized black holes

Valeri Frolov University of Alberta

November 21, 2013

PIRSA:13110066

Strong Gravity

There exist evidences that magnetic field in the vicinity of astrophysical black holes plays an important role. In particular it is required for explanation of such phenomenon as jet formation. Study of such problems in all their complexity requires 3D numerical simulations of the magnetohydrodynamics in a strong gravitational field. Quite often when dealing with such a complicated problem it is instructive to consider first its simplifications, which can be treated either analytically, or by integrating ordinary differential equations. Motion of a charged particle in a weakly magnetized black hole is an important example. We consider a non-rotating black hole in the weak magnetic field which is homogeneous at infinity. In the talk I discuss the following problems: How does such a magnetic field affect charged particle motion in the equatorial plane? How does it change the radius of the innermost stable circular orbits (ISCO) and period of rotation? I shall demonstratethat the magnetic field increases the efficiency of the energy extraction from the black hole and that magnetized black holes can be used as "particle accelerators". Finally, I shall discuss out-of-equatorial-plane motion and demonstrate that it is chaotic. Possible applications of these results to astrophysics are briefly discussed.
13/14 PSI - Condensed Matter - Lecture 9

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 21, 2013

PIRSA:13110037
13/14 PSI - Quantum Field Theory II - Lecture 9

Francois David CEA Saclay

November 21, 2013

PIRSA:13110018
Quantum Adversary (Upper) Bound

Shelby Kimmel Massachusetts Institute of Technology (MIT)

November 20, 2013

PIRSA:13110090

Quantum Information

I discuss a technique - the quantum adversary upper bound - that uses the structure of quantum algorithms to gain insight into the quantum query complexity of Boolean functions. Using this bound, I show that there must exist an algorithm for a certain Boolean formula that uses a constant number of queries. Since the method is non-constructive, it does not give information about the form of the algorithm. After describing the technique and applying it to a class of functions, I will outline quantum algorithms that match the non-constructive bound.
Light and matter: towards macroscopic quantum systems

Jacob Taylor Office of Science and Technology Policy

November 20, 2013

PIRSA:13110060

Quantum Information

Advances in quantum engineering and material science are enabling new approaches for building systems that behave quantum mechanically on long time scales and large length scales. I will discuss how microwave and optical technologies in particular are leading to new domains of many-body physics, both classical and quantum, using photons and phonons as the constituent particles. Furthermore, I will highlight practical consequences of these advances, including improved force and acceleration sensing, efficient signal transduction, and topologically robust photonic circuits. Finally, I will consider how such large quantum systems may help us measure and constrain theories of quantum gravity and gravity-induced decoherence.
13/14 PSI - Condensed Matter - Lecture 8

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 20, 2013

PIRSA:13110036
13/14 PSI - Quantum Field Theory II - Lecture 8

Francois David CEA Saclay

November 20, 2013

PIRSA:13110017
General Relativity for Cosmology - Lecture 18

Achim Kempf University of Waterloo

November 19, 2013

PIRSA:13110005
The Amplitude Mode in Condensed Matter : Higgs Hunting on a Budget

Daniel Arovas University of California, San Diego

November 19, 2013

PIRSA:13110054

Condensed Matter

The amplitude mode is a ubiquitous phenomenon in systems with broken continuous symmetry and effective relativistic dynamics, and has been observed in magnets, charge density waves, cold atom systems, and superconductors. It is a simple analog of the Higgs boson of particle physics. I will discuss the properties of the amplitude mode and its somewhat surprising visibility in two-dimensional systems, recently confirmed in cold atom experiments. The behavior in the vicinity of a quantum critical point will be stressed, comparing theoretical, numerical, and experimental results.
New Light Species and the CMB - Joint Cosmology/Particle Physics Seminar

Christopher Brust

November 19, 2013

PIRSA:13110051

Particle Physics

The effective number of neutrino species in our universe, Neff, is capable of probing the presence of new light or massless species in our universe. I will first review relevant facts about both CMB measurements of new light species and thermodynamics in the early universe. Then, I will present the effects of many models of BSM physics containing new light species on the CMB, including models containing eV-scale sterile neutrinos compatible with anomalies in neutrino experiments, and interpret the compatibility of the parameter space of these models in terms of the recent results from the Planck satellite. I will argue that the bounds on couplings obtained from the Planck measurement of the CMB are competitive with bounds coming from other areas of physics.
13/14 PSI - Condensed Matter - Lecture 7

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 19, 2013

PIRSA:13110035

Title	Date	Collection	Type	Info
Dimensional reduction in the sky	2013‑11‑21	Quantum Gravity	Scientific Series	View details
Charged particle motion in magnetized black holes	2013‑11‑21	Strong Gravity	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 9	2013‑11‑21	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 9	2013‑11‑21	13/14 PSI - Quantum Field Theory II	Course	View details
Quantum Adversary (Upper) Bound	2013‑11‑20	Perimeter Institute Quantum Discussions	Scientific Series	View details
Light and matter: towards macroscopic quantum systems	2013‑11‑20	Colloquium	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 8	2013‑11‑20	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 8	2013‑11‑20	13/14 PSI - Quantum Field Theory II	Course	View details
General Relativity for Cosmology - Lecture 18	2013‑11‑19	General Relativity for Cosmology - 2013	Course	View details
The Amplitude Mode in Condensed Matter : Higgs Hunting on a Budget	2013‑11‑19	Quantum Matter	Scientific Series	View details
New Light Species and the CMB - Joint Cosmology/Particle Physics Seminar	2013‑11‑19	Particle Physics	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 7	2013‑11‑19	13/14 PSI - Condensed Matter	Course	View details

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