Talks

10861 - 10872 of 16889 Results

Statistical Mechanics - Lecture 5

John Berlinsky McMaster University

November 16, 2012

PIRSA:12110023
Quantum Field Theory 2 - Lecture 5

Francois David CEA Saclay

November 16, 2012

PIRSA:12110004

Quantum Fields and Strings
Canonical tensor models with local time

Naoki Sasakura Yukawa Institute for Theoretical Physics

November 15, 2012

PIRSA:12110065

Quantum Gravity
Detecting Gravitational Waves with Millisecond Pulsars

Paul Demorest National Radio Astronomy Observatory

November 15, 2012

PIRSA:12110044

Strong Gravity
Solid of Inflation: An alternative symmetry breaking pattern for an EFT of inflation

Solomon Endlich Stanford University

November 15, 2012

PIRSA:13010005

Cosmology
Statistical Mechanics - Lecture 4

John Berlinsky McMaster University

November 15, 2012

PIRSA:12110022
Quantum Field Theory 2 - Lecture 4

Francois David CEA Saclay

November 15, 2012

PIRSA:12110003

Quantum Fields and Strings
Modified Gravity, Dark Matter and Dark Energy: Deep Mysteries of the Universe

John Moffat Perimeter Institute for Theoretical Physics

November 14, 2012

PIRSA:12110074

Cosmology
Massive gravitons, the cosmological constant and new directions in gravity

November 14, 2012

PIRSA:12110061

Cosmology
Statistical Mechanics - Lecture 3

John Berlinsky McMaster University

November 14, 2012

PIRSA:12110021
Quantum Field Theory 2 - Lecture 3

Francois David CEA Saclay

November 14, 2012

PIRSA:12110002

Quantum Fields and Strings
Quasiprobability representations of qubits

November 13, 2012

PIRSA:12110070

Statistical Mechanics - Lecture 5

John Berlinsky McMaster University

November 16, 2012

PIRSA:12110023
Quantum Field Theory 2 - Lecture 5

Francois David CEA Saclay

November 16, 2012

PIRSA:12110004

Quantum Fields and Strings
Canonical tensor models with local time

Naoki Sasakura Yukawa Institute for Theoretical Physics

November 15, 2012

PIRSA:12110065

Quantum Gravity

Tensor models are generalization of matrix models, and are studied as discrete models for quantum gravity for more than two-dimensions. Among them, the rank-three tensor models can be interpreted as theories of dynamical fuzzy spaces, and they generally have the feature of
respecting symmetries. In this talk, after briefly reviewing some results on Euclidean models such as spontaneous generation of fuzzy spaces and Euclidean general relativity respecting the diffeomorphism symmetry on them, I will present a way to introduce “local” time to the rank-three tensor models by constructing “local” Hamiltonians. The consistency among the multiple ways of local time evolutions is guaranteed by the on-shell closure of the constraint algebra among the
local Hamiltonians and the symmetry generators of the tensor models. The constraint algebra is shown to approach the DeWitt algebra in a formal continuum limit. I will also discuss the two-fold uniqueness of the local Hamiltonians, and will briefly show some preliminary results on the quantization.
Detecting Gravitational Waves with Millisecond Pulsars

Paul Demorest National Radio Astronomy Observatory

November 15, 2012

PIRSA:12110044

Strong Gravity

Millisecond spin-period radio pulsars provide us with unique astronomical "laboratories" for exploring fundamental physics in a variety of ways -- from the physics of matter at super-nuclear density, to experimental tests of gravity. They have also provided the only experimental evidence so far for the existence of gravitational waves (GW). A set of millisecond pulsars acting as precise astronomical clocks may also be used as a direct GW detector, sensitive to the nanohertz-frequency GW expected to be emitted by supermassive black hole binary systems or other more exotic sources. In this talk I will present the project status and recent GW upper limits from the NANOGrav project. I will also discuss expected near-future improvements in the measurement, including recent work aimed at better characterizing and mitigating the effect of multi-path propagation effects in the interstellar medium.
Solid of Inflation: An alternative symmetry breaking pattern for an EFT of inflation

Solomon Endlich Stanford University

November 15, 2012

PIRSA:13010005

Cosmology

In this talk I will discuss a cosmological model where primordial inflation is driven by a `solid', defined as a system of three derivatively coupled scalar fields obeying certain symmetries and spontaneously breaking a certain subgroup of these. The symmetry breaking pattern differs drastically from that of standard inflationary models: time translations are unbroken. This prevents our model from fitting into the standard effective field theory description of adiabatic perturbations. Consequently, it exhibits a novel non-Gaussian `shape'.
Statistical Mechanics - Lecture 4

John Berlinsky McMaster University

November 15, 2012

PIRSA:12110022
Quantum Field Theory 2 - Lecture 4

Francois David CEA Saclay

November 15, 2012

PIRSA:12110003

Quantum Fields and Strings
Modified Gravity, Dark Matter and Dark Energy: Deep Mysteries of the Universe

John Moffat Perimeter Institute for Theoretical Physics

November 14, 2012

PIRSA:12110074

Cosmology
Massive gravitons, the cosmological constant and new directions in gravity

November 14, 2012

PIRSA:12110061

Cosmology

The solutions to the cosmological constant problems may involve modifying the very long-range dynamics of gravity by adding new degrees of freedom. As an example of a conservative and minimal such modification, we consider the possibility that the graviton has a very small mass. Massive gravity has received renewed interest due to recent advances which have resolved its traditional problems. This kind of modification has some peculiar and unexpected features, and it points us towards a universe which looks quite unfamiliar.
Support for this colloquium is provided by The Templeton Frontiers Program.
Statistical Mechanics - Lecture 3

John Berlinsky McMaster University

November 14, 2012

PIRSA:12110021
Quantum Field Theory 2 - Lecture 3

Francois David CEA Saclay

November 14, 2012

PIRSA:12110002

Quantum Fields and Strings
Quasiprobability representations of qubits

November 13, 2012

PIRSA:12110070

Negativity in a quasi-probability representation is typically interpreted as an indication of nonclassical behavior. However, this does not preclude bases that are non-negative from having interesting applications---the single-qubit stabilizer states have non-negative Wigner functions and yet play a fundamental role in many quantum information tasks. We determine what other sets of quantum states and measurements of a qubit can be non-negative in a quasiprobability representation, and identify nontrivial groups of unitary transformations that permute such states. These sets of states and measurements are analogous to the single-qubit stabilizer states. We show that no quasiprobability representation of a qubit can be non-negative for more than two bases in any plane of the Bloch sphere. Furthermore, there is a single family of sets of four bases that can be non-negative in an arbitrary quasiprobability representation of a qubit. We provide an exhaustive list of the sets of single-qubit bases that are nonnegative in some quasiprobability representation and are also closed under a group of unitary transformations, revealing two families of such sets of three bases. We also show that not all two-qubit Clifford transformations can preserve non-negativity in any quasiprobability representation that is non-negative for the computational basis. This is in stark contrast to the qutrit case, in which the discrete Wigner function is non-negative for all n-qutrit stabilizer states and Clifford transformations. We also provide some evidence that extending the other sets of non-negative single-qubit states to multiple qubits does not give entangled states.

Title	Date	Collection	Type	Info
Statistical Mechanics - Lecture 5	2012‑11‑16	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 5	2012‑11‑16	12/13 PSI - Quantum Field Theory 2	Course	View details
Canonical tensor models with local time	2012‑11‑15	Quantum Gravity	Scientific Series	View details
Detecting Gravitational Waves with Millisecond Pulsars	2012‑11‑15	Strong Gravity	Scientific Series	View details
Solid of Inflation: An alternative symmetry breaking pattern for an EFT of inflation	2012‑11‑15	Cosmology and Gravitation	Scientific Series	View details
Statistical Mechanics - Lecture 4	2012‑11‑15	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 4	2012‑11‑15	12/13 PSI - Quantum Field Theory 2	Course	View details
Modified Gravity, Dark Matter and Dark Energy: Deep Mysteries of the Universe	2012‑11‑14	Cosmology and Gravitation	Other	View details
Massive gravitons, the cosmological constant and new directions in gravity	2012‑11‑14	Colloquium	Scientific Series	View details
Statistical Mechanics - Lecture 3	2012‑11‑14	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 3	2012‑11‑14	12/13 PSI - Quantum Field Theory 2	Course	View details
Quasiprobability representations of qubits	2012‑11‑13	Quantum Foundations	Scientific Series	View details

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