Scientific Series

Displaying 3421 - 3432 of 4903

Superradiant Superconductivity

Baskaran Ganapathy Institute of Mathematical Sciences
November 16, 2012

PIRSA:12110071
Condensed Matter
Canonical tensor models with local time

Naoki Sasakura Yukawa Institute for Theoretical Physics
November 15, 2012

PIRSA:12110065
General Relativity & Quantum Cosmology
Detecting Gravitational Waves with Millisecond Pulsars

Paul Demorest National Radio Astronomy Observatory (NRAO)
November 15, 2012

PIRSA:12110044
General Relativity & Quantum Cosmology
Solid of Inflation: An alternative symmetry breaking pattern for an EFT of inflation

Solomon Endlich Stanford University
November 15, 2012

PIRSA:13010005
Astrophysics
Massive gravitons, the cosmological constant and new directions in gravity
November 14, 2012

PIRSA:12110061
Astrophysics
Quasiprobability representations of qubits

November 13, 2012

PIRSA:12110070
Anomaly-induced transport and thermodynamics

Kristan Jensen University of Victoria
November 13, 2012

PIRSA:12110047
High Energy Physics
Stealthy, Composite Stops

Philip Tanedo Cornell University
November 13, 2012

PIRSA:12110063
High Energy Physics
Recent progress on de Sitter S-matrix

Ian Morrison West Chester University
November 13, 2012

PIRSA:12110043
Astrophysics
Geometric algebra techniques in flux compactifications

Calin Lazaroiu Horia Hulubei National Institute of Physics and Nuclear Engineering
November 09, 2012

PIRSA:12110058
Mathematical Physics
Dynamical evaporation of quantum horizons
November 08, 2012

PIRSA:12110064
General Relativity & Quantum Cosmology
An introduction to quantum channels and their capacities

Graeme Smith Institute for Quantum Computing (IQC)
November 07, 2012

PIRSA:12110066
Quantum Physics

Superradiant Superconductivity

Baskaran Ganapathy Institute of Mathematical Sciences
November 16, 2012

PIRSA:12110071
Condensed Matter
In Dicke Superradiance, a collection of 2-level atoms interacting with a single boson mode acquires, through quantum coherence, an enhanced emission property and a rich dynamics. We suggest possibility of Dicke superradiance in a BCS superconductor. The necessary 2-level atoms are identified with Anderson pseudo spins seeing a self consistent mean field in k-space. A way to couple these 2-level bose atoms to an external boson mode and create a novel non equilibrium superradiant superconductivity (SRSC) is suggested. Our mechanism offers a hope to realize transient superconductivity, even at room temperatures, in the pseudo gap phase of certain underdoped cuprates. Recent experiments are briefly discussed in this light. Further SRSC exhibits interesting quantum entanglement and superfluorescence properties.
Canonical tensor models with local time

Naoki Sasakura Yukawa Institute for Theoretical Physics
November 15, 2012

PIRSA:12110065
General Relativity & Quantum Cosmology
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 (NRAO)
November 15, 2012

PIRSA:12110044
General Relativity & Quantum Cosmology
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
Astrophysics
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'.
Massive gravitons, the cosmological constant and new directions in gravity
November 14, 2012

PIRSA:12110061
Astrophysics
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.
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.
Anomaly-induced transport and thermodynamics

Kristan Jensen University of Victoria
November 13, 2012

PIRSA:12110047
High Energy Physics
I will discuss recent progress in the study of anomaly-induced transport, focusing on the chiral vortical effect in 3+1 dimensions. Most of my discussion will be framed in light of a larger story, namely progress in making exact statements about finite-temperature quantum field theory, for which the chiral magnetic and vortical effects are instructive prototypes.
Stealthy, Composite Stops

Philip Tanedo Cornell University
November 13, 2012

PIRSA:12110063
High Energy Physics
Light third generation superpartners are one way to avoid bounds on new physics from the early LHC. We will review the theory and phenomenology of light stops and highlight a particular UV model based a partially composite electroweak sector through Seiberg duality.
Recent progress on de Sitter S-matrix

Ian Morrison West Chester University
November 13, 2012

PIRSA:12110043
Astrophysics
The de Sitter S-matrix provides a gauge-invariant and field redefinition-invariant window into de Sitter QFTs and may provide a crucial entry in any dS/CFT dictionary. In this talk I will summarize recent progress on developing the S-matrix for theories with gauge fields and perturbative gravity. Nonrenormalization theorems, hints of supersymmetry, and perturbative stability will be discussed.
Geometric algebra techniques in flux compactifications

Calin Lazaroiu Horia Hulubei National Institute of Physics and Nuclear Engineering
November 09, 2012

PIRSA:12110058
Mathematical Physics
Using techniques originating in a certain approach to Clifford bundles known as "geometric algebra", I discuss a geometric reformulation of constrained generalized Killing spinor equations which proves to be particularly effective in the study and classification of supersymmetric flux compactifications of string and M-theory. As an application, I discuss the most general N=2 compactifications of M-theory to three dimensions, which were never studied in full generality before. I also touch upon the connection of such techniques with a certain variant of the quantization of spin systems.
Dynamical evaporation of quantum horizons
November 08, 2012

PIRSA:12110064
General Relativity & Quantum Cosmology
We describe of the evaporation process as driven by the dynamical evolution of the quantum gravitational degrees of freedom resident at the horizon, as identified by the Loop Quantum Gravity kinematics. Using a parallel with the Brownian motion, we interpret the first law of quantum dynamical horizon in terms of a fluctuation-dissipation relation applied to this fundamental discrete structure. In this way, the horizon evolution is described in terms of relaxation to an equilibrium state balanced by the excitation of Planck scale constituents of the horizon. We show how from this setting the emergence of several conservative scenarios for the final stage of the evaporation process can be microscopically derived. Namely, the leakage of part of the horizon quantum geometry information prior to the Planckian phase and the stabilization of the hole surface shrinkage forming a massive remnant, which can eventually decay, are shown to take place.
An introduction to quantum channels and their capacities

Graeme Smith Institute for Quantum Computing (IQC)
November 07, 2012

PIRSA:12110066
Quantum Physics
A quantum communication channel can be put to many uses: it can transmit classical information, private classical information, or quantum information. It can be used alone, with shared entanglement, or together with other channels. For each of these settings there is a capacity that quantifies a channel's fundamental potential for communication. In this introductory talk, I will discuss what we known about the various capacities of a quantum channel, including a discussion of synergies between different channels and related additivity questions.

Title	Speaker(s)	Date	Talk Type	Info link
Superradiant Superconductivity	Baskaran Ganapathy	2012-11-16	Scientific Series	View details
Canonical tensor models with local time	Naoki Sasakura	2012-11-15	Scientific Series	View details
Detecting Gravitational Waves with Millisecond Pulsars	Paul Demorest	2012-11-15	Scientific Series	View details
Solid of Inflation: An alternative symmetry breaking pattern for an EFT of inflation	Solomon Endlich	2012-11-15	Scientific Series	View details
Massive gravitons, the cosmological constant and new directions in gravity		2012-11-14	Scientific Series	View details
Quasiprobability representations of qubits		2012-11-13	Scientific Series	View details
Anomaly-induced transport and thermodynamics	Kristan Jensen	2012-11-13	Scientific Series	View details
Stealthy, Composite Stops	Philip Tanedo	2012-11-13	Scientific Series	View details
Recent progress on de Sitter S-matrix	Ian Morrison	2012-11-13	Scientific Series	View details
Geometric algebra techniques in flux compactifications	Calin Lazaroiu	2012-11-09	Scientific Series	View details
Dynamical evaporation of quantum horizons		2012-11-08	Scientific Series	View details
An introduction to quantum channels and their capacities	Graeme Smith	2012-11-07	Scientific Series	View details

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Superradiant Superconductivity

Canonical tensor models with local time

Detecting Gravitational Waves with Millisecond Pulsars

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

Massive gravitons, the cosmological constant and new directions in gravity

Quasiprobability representations of qubits

Anomaly-induced transport and thermodynamics

Stealthy, Composite Stops

Recent progress on de Sitter S-matrix

Geometric algebra techniques in flux compactifications

Dynamical evaporation of quantum horizons

An introduction to quantum channels and their capacities

Superradiant Superconductivity

Canonical tensor models with local time

Detecting Gravitational Waves with Millisecond Pulsars

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

Massive gravitons, the cosmological constant and new directions in gravity

Quasiprobability representations of qubits

Anomaly-induced transport and thermodynamics

Stealthy, Composite Stops

Recent progress on de Sitter S-matrix

Geometric algebra techniques in flux compactifications

Dynamical evaporation of quantum horizons

An introduction to quantum channels and their capacities