Talks

10069 - 10080 of 18369 Results

Cosmic Variance from Superhorizon Mode Coupling

Elliot Nelson

January 23, 2014

PIRSA:14010107

Astrophysics
13/14 PSI - Gravitational Physics Review - Lecture 14

Ruth Gregory King's College London

January 23, 2014

PIRSA:14010044
13/14 PSI - Standard Model Review - Lecture 14

Paul Langacker Institute for Advanced Study (IAS)

January 23, 2014

PIRSA:14010025
Hardness of correcting errors on a stabilizer code

Pavithran Iyer

January 22, 2014

PIRSA:14010099

Quantum Physics
13/14 PSI - Foundations of Quantum Mechanics - Lecture 13

Lucien Hardy Perimeter Institute for Theoretical Physics

January 22, 2014

PIRSA:14010062
13/14 PSI - Gravitational Physics Review - Lecture 13

Ruth Gregory King's College London

January 22, 2014

PIRSA:14010043
13/14 PSI - Standard Model Review - Lecture 13

Paul Langacker Institute for Advanced Study (IAS)

January 22, 2014

PIRSA:14010024
Introduction to Quantum Field Theory for Cosmology - Lecture 5

Achim Kempf University of Waterloo

January 21, 2014

PIRSA:14010002
Does the Quantum Particle know its own Energy?

Rafael Sorkin Perimeter Institute for Theoretical Physics

January 21, 2014

PIRSA:14010106

Quantum Physics
Boundaries and Defects in 4d N=4 SYM

Masahito Yamazaki University of Tokyo

January 21, 2014

PIRSA:14010086

High Energy Physics
Paying the price of naturalness with a supersymmetric twin Higgs

Kiel Howe Stanford University

January 21, 2014

PIRSA:14010105

Condensed Matter
13/14 PSI - Foundations of Quantum Mechanics - Lecture 12

Lucien Hardy Perimeter Institute for Theoretical Physics

January 21, 2014

PIRSA:14010061

Cosmic Variance from Superhorizon Mode Coupling

Elliot Nelson

January 23, 2014

PIRSA:14010107

Astrophysics

We observe a finite subvolume of the universe, so CMB and large scale structure data may give us either a representative or a biased sample of statistics in the larger universe. Mode coupling (non-Gaussianity) in the primordial perturbations can introduce a bias of parameters measured in any subvolume due to coupling to superhorizon background modes longer than the size of the subvolume. This leads to a "cosmic variance" of statistics on smaller scales, as the long-wavelength background modes vary around the global mean. We study this bias for local non-Gaussianity and quantify how observed statistics such as the power spectrum of the primordial perturbations, spectral index (scale-dependence in the power spectrum), amplitude of non-Gaussianity, dark matter halo power spectrum, and primordial tensor modes, can differ from the same quantities averaged throughout a volume much larger than the observable universe. More general kinds of mode coupling can change the relative sensitivity to different background modes. Finally, we consider what observations can tell us about the possibility of biasing from superhorizon modes."
13/14 PSI - Gravitational Physics Review - Lecture 14

Ruth Gregory King's College London

January 23, 2014

PIRSA:14010044
13/14 PSI - Standard Model Review - Lecture 14

Paul Langacker Institute for Advanced Study (IAS)

January 23, 2014

PIRSA:14010025
Hardness of correcting errors on a stabilizer code

Pavithran Iyer

January 22, 2014

PIRSA:14010099

Quantum Physics

Problems in computer science are often classified based on the scaling of the runtimes for algorithms that can solve the problem. Easy problems are efficiently solvable but often in physics we encounter problems that take too long to be solved on a classical computer. Here we look at one such problem in the context of quantum error correction. We will further show that no efficient algorithm for this problem is likely to exist. We will address the computational hardness of a decoding problem, pertaining to quantum stabilizer codes considering independent X and Z errors on each qubit. Much like classical linear codes, errors are detected by measuring certain check operators which yield an error syndrome, and the decoding problem consists of determining the most likely recovery given the syndrome. The corresponding classical problem is known to be NP-Complete, and a similar decoding problem for quantum codes is known to be NP-Complete too. However, this decoding strategy is not optimal in the quantum setting as it does not take into account error degeneracy, which causes distinct errors to have the same effect on the code. Here, we show that optimal decoding of stabilizer codes is computationally much harder than optimal decoding of classical linear codes, it is #P-Complete.
13/14 PSI - Foundations of Quantum Mechanics - Lecture 13

Lucien Hardy Perimeter Institute for Theoretical Physics

January 22, 2014

PIRSA:14010062
13/14 PSI - Gravitational Physics Review - Lecture 13

Ruth Gregory King's College London

January 22, 2014

PIRSA:14010043
13/14 PSI - Standard Model Review - Lecture 13

Paul Langacker Institute for Advanced Study (IAS)

January 22, 2014

PIRSA:14010024
Introduction to Quantum Field Theory for Cosmology - Lecture 5

Achim Kempf University of Waterloo

January 21, 2014

PIRSA:14010002
Does the Quantum Particle know its own Energy?

Rafael Sorkin Perimeter Institute for Theoretical Physics

January 21, 2014

PIRSA:14010106

Quantum Physics

If a wave function does not describe microscopic reality then what does? Reformulating quantum mechanics in path-integral terms leads to a notion of ``precluded event" and thence to the proposal that quantal reality differs from classical reality in the same way as a set of worldlines differs from a single worldline. One can then ask, for example, which sets of electron trajectories correspond to a Hydrogen atom in its ground state and how they differ from those of an excited state. We address the analogous questions for simple model that replaces the electron by a particle hopping (in discrete time) on a circular lattice.
Boundaries and Defects in 4d N=4 SYM

Masahito Yamazaki University of Tokyo

January 21, 2014

PIRSA:14010086

High Energy Physics

We discuss boundary conditions and domain walls in 4d N=4 SYM, focusing on those preserving 4 supercharges. Along the way we revisit the old problem of the quantum-corrected moduli space of 3d N=2 theories.
Paying the price of naturalness with a supersymmetric twin Higgs

Kiel Howe Stanford University

January 21, 2014

PIRSA:14010105

Condensed Matter

What is the price of naturalness? In minimal extensions of the standard model, stringent limits on new colored particles and measurements of Higgs properties from the LHC severely challenge the hypothesis of naturalness of the electroweak scale. However, these measurements also provide unprecedented guidance in exploring non-minimal models of new electroweak physics. The supersymmetric twin Higgs provides a concrete example where few-percent level tuning remains compatible with superpartner limits and Higgs physics as well as gauge coupling unification and other successes of the MSSM. Studying such models in detail is crucial to understanding the role naturalness will play as a motivating principle for future searches at the 13 TeV LHC and beyond.
13/14 PSI - Foundations of Quantum Mechanics - Lecture 12

Lucien Hardy Perimeter Institute for Theoretical Physics

January 21, 2014

PIRSA:14010061

Title	Date	Collection	Type	Info
Cosmic Variance from Superhorizon Mode Coupling	2014‑01‑23	Cosmology and Gravitation	Scientific Series	View details
13/14 PSI - Gravitational Physics Review - Lecture 14	2014‑01‑23	13/14 PSI - Gravitational Physics Review	Course	View details
13/14 PSI - Standard Model Review - Lecture 14	2014‑01‑23	13/14 PSI - Standard Model Review	Course	View details
Hardness of correcting errors on a stabilizer code	2014‑01‑22	Perimeter Institute Quantum Discussions	Scientific Series	View details
13/14 PSI - Foundations of Quantum Mechanics - Lecture 13	2014‑01‑22	13/14 PSI - Foundations of Quantum Mechanics	Course	View details
13/14 PSI - Gravitational Physics Review - Lecture 13	2014‑01‑22	13/14 PSI - Gravitational Physics Review	Course	View details
13/14 PSI - Standard Model Review - Lecture 13	2014‑01‑22	13/14 PSI - Standard Model Review	Course	View details
Introduction to Quantum Field Theory for Cosmology - Lecture 5	2014‑01‑21	Quantum Field Theory for Cosmology - 2014	Course	View details
Does the Quantum Particle know its own Energy?	2014‑01‑21	Quantum Foundations	Scientific Series	View details
Boundaries and Defects in 4d N=4 SYM	2014‑01‑21	Quantum Fields and Strings	Scientific Series	View details
Paying the price of naturalness with a supersymmetric twin Higgs	2014‑01‑21	Quantum Matter	Scientific Series	View details
13/14 PSI - Foundations of Quantum Mechanics - Lecture 12	2014‑01‑21	13/14 PSI - Foundations of Quantum Mechanics	Course	View details

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Format results

Cosmic Variance from Superhorizon Mode Coupling

13/14 PSI - Gravitational Physics Review - Lecture 14

13/14 PSI - Standard Model Review - Lecture 14

Hardness of correcting errors on a stabilizer code

13/14 PSI - Foundations of Quantum Mechanics - Lecture 13

13/14 PSI - Gravitational Physics Review - Lecture 13

13/14 PSI - Standard Model Review - Lecture 13

Introduction to Quantum Field Theory for Cosmology - Lecture 5

Does the Quantum Particle know its own Energy?

Boundaries and Defects in 4d N=4 SYM

Paying the price of naturalness with a supersymmetric twin Higgs

13/14 PSI - Foundations of Quantum Mechanics - Lecture 12

Cosmic Variance from Superhorizon Mode Coupling

13/14 PSI - Gravitational Physics Review - Lecture 14

13/14 PSI - Standard Model Review - Lecture 14

Hardness of correcting errors on a stabilizer code

13/14 PSI - Foundations of Quantum Mechanics - Lecture 13

13/14 PSI - Gravitational Physics Review - Lecture 13

13/14 PSI - Standard Model Review - Lecture 13

Introduction to Quantum Field Theory for Cosmology - Lecture 5

Does the Quantum Particle know its own Energy?

Boundaries and Defects in 4d N=4 SYM

Paying the price of naturalness with a supersymmetric twin Higgs

13/14 PSI - Foundations of Quantum Mechanics - Lecture 12