Talks

12493 - 12504 of 19958 Results

Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University

April 30, 2013

PIRSA:13040141

High Energy Physics
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington

April 30, 2013

PIRSA:13040126

High Energy Physics
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London

April 30, 2013

PIRSA:13040128

Astrophysics
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong

April 29, 2013

PIRSA:13040112

Quantum Physics
12/13 PSI - Explorations in String Theory Lecture 15

Pedro Vieira Perimeter Institute for Theoretical Physics

April 26, 2013

PIRSA:13040102

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 15

Matthew Johnson York University

April 26, 2013

PIRSA:13040080

Astrophysics
12/13 PSI - Explorations in Condensed Matter Lecture 15

Guifre Vidal Alphabet (United States)

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

April 26, 2013

PIRSA:13040061

Condensed Matter
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Pat Clancy University of Toronto

April 25, 2013

PIRSA:13040137

Condensed Matter
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

April 25, 2013

PIRSA:13040132

High Energy Physics

Condensed Matter
Tensor Networks: an Overview

Lukasz Cincio Los Alamos National Laboratory

April 25, 2013

PIRSA:13040131

Quantum Physics
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Katharina Fristsch McMaster University

April 25, 2013

PIRSA:13040136

Condensed Matter
Absence of Pauling's Residual Entropy in Dy2Ti2O

Jan Kycia University of Waterloo

April 25, 2013

PIRSA:13040130

Condensed Matter

Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University

April 30, 2013

PIRSA:13040141

High Energy Physics

It has been known for twenty years that a class of two-dimensional gauge theories are intimately connected to toric geometry, as well as to hypersurfaces or complete intersections in a toric varieties, and to generalizations thereof. Under renormalization group flow, the two-dimensional gauge theory flows to a conformal field theory that describes string propagation on the associated geometry. This provides a connection between certain quantities in the gauge theory and topological invariants of the associated geometry. In this talk, I will explain how recent results show that, for Calabi-Yau geometries, the partition function for each gauge theory computes the Kahler potential on the Kahler moduli of the associated geometry. The result is expressed in terms of a Barnes' integral and is readily evaluated in a series expansion around special points in the moduli space (e.g., large volume), providing a fairly efficient way to compute Gromov-Witten invariants of the associated geometry.
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington

April 30, 2013

PIRSA:13040126

High Energy Physics

In this talk, I will start with briefly introducing some universal physics behind quantum hall and topological insulator , which inspired a BSM flavor model. It intimately relates deconstructed little Higgs to flavor structure: fermion masses, CKM etc. This new cousin of little Higgs, we call it little flavor, shares a 10-20 Tev cut-off scale with little Higgs, so as to explain flavor structure at surprisingly low scale without rising FCNC problem.
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London

April 30, 2013

PIRSA:13040128

Astrophysics

The non-Gaussian statistics of the primordial density perturbation have become a key test of the inflationary scenario of the very early universe. Currently many techniques are used to calculate the non-Gaussian signatures of a given model of inflation. In particular, simple super-horizon techniques such as the deltaN formalism are often used for models with more than one field, while more technical field theory techniques, referred to as the In-In formalism, are typically used for models where the quantum sub-horizon evolution is important. Recently we have been developing an alternative point of view, called the transport approach. This framework highlights the connections between these other techniques and unifies them. Moreover, since it reduces the problem of calculating the statistics to that of solving a set of coupled ODEs, numerical implementations of the system are extremely simple.
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong

April 29, 2013

PIRSA:13040112

Quantum Physics

A recent development in information theory is the generalisation of quantum Shannon information theory to the operationally motivated smooth entropy information theory, which originates in quantum cryptography research. In a series of papers the first steps have been taken towards creating a statistical mechanics based on smooth entropy information theory. This approach turns out to allow us to answer questions one might not have thought were possible in statistical mechanics, such as how much work one can extract in a given realisation, as a function of the failure-probability. This is in contrast to the standard approach which makes statements about average work. Here we formulate the laws of thermodynamics that this new approach gives rise to. We show in particular that the Second Law needs to be tightened. The new laws are motivated by our main quantitative result which states how much work one can extract or must invest in order to affect a given state change with a given probability of success. For systems composed of very large numbers of identical and uncorrelated subsystems, which we call the von Neumann regime, we recover the standard von Neumann entropy statements.

Joint work with Egloff, Renner and Vedral

http://arxiv.org/abs/1207.0434
12/13 PSI - Explorations in String Theory Lecture 15

Pedro Vieira Perimeter Institute for Theoretical Physics

April 26, 2013

PIRSA:13040102

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 15

Matthew Johnson York University

April 26, 2013

PIRSA:13040080

Astrophysics
12/13 PSI - Explorations in Condensed Matter Lecture 15

Guifre Vidal Alphabet (United States)

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

April 26, 2013

PIRSA:13040061

Condensed Matter
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Pat Clancy University of Toronto

April 25, 2013

PIRSA:13040137

Condensed Matter

The physics of iridium-based 5d transition metal oxides has attracted significant interest due to the potential for exotic magnetic and electronic ground states driven by strong spin-orbit coupling effects. Among the most extensively studied iridates is the layered perovskite Sr2IrO4, which was recently proposed as the first experimental realization of a novel Jeff=1/2 spin-orbital Mott insulating state. Intriguing similarities between Sr2IrO4 and La2CuO4, the parent compound of the high-Tc cuprates, have also led to speculation that it may be possible to induce superconductivity in this system through chemical doping. We have investigated the magnetic properties of the doped system Sr2Ir1-xRhxO4 using a combination of resonant magnetic x-ray scattering (RMXS), resonant inelastic x-ray scattering (RIXS), and x-ray absorption spectroscopy (XAS) techniques. These measurements reveal the effect of Rh-doping on the magnetic structure, phase diagram, and characteristic magnetic excitations of Sr2IrO4, and provide fundamental information about the role of quenched Rh impurities.
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

April 25, 2013

PIRSA:13040132

High Energy Physics

Condensed Matter

In this talk I will briefly review the polaron physics, which has helped theorists to conceive the BCS theory of conventional superconductors as well as experimentalists to discover high temperature superconductors in the cuprates. Specifically I will talk about how charge carriers obtain their
masses from coupling to the phonon field in one, two, three or higher dimensions. More recently, there is increasing interest in topological insulators where a gap can be opened which may suggest new version of Higgs mechanism in condensed matter.
Tensor Networks: an Overview

Lukasz Cincio Los Alamos National Laboratory

April 25, 2013

PIRSA:13040131

Quantum Physics

Tensor network algorithms provide highly competitive tools for analyzing ground state properties of quantum lattice models in one and two spatial dimensions. The most notable examples involve matrix product states, projected entangled pair states and multiscale entanglement renormalization ansatz. The key underlying idea of all the approaches is to decompose a quantum many-body state into a carefully chosen network of tensors.
In this talk I will give an introduction to the subject and show how tensor networks can be used to characterize topological order.
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Katharina Fristsch McMaster University

April 25, 2013

PIRSA:13040136

Condensed Matter

The ground state of the candidate spin liquid pyrochlore magnet Tb2Ti2O7 (TTO) has been long debated. Despite theoretical expectations of magnetic order below ~1K based on classical Ising-like Tb3+ spins, earlier muSR and neutron scattering experiments showed no long range order down to 50mK. This motivated two theoretical scenarios to account for the apparently disordered ground state: a quantum spin ice scenario and a non-magnetic singlet ground state. I will discuss new neutron scattering measurements on TTO that show short range spin correlations developing below ~ 0.5 K with a (½, ½, ½) ordering wavevector, and a concomitant opening of a spin gap across most of the Brillouin zone. Our measurements also refine the crystal field ground state for Tb3+ in TTO and in its sister, “soft” spin ice compound Tb2Sn2O7.
Absence of Pauling's Residual Entropy in Dy2Ti2O

Jan Kycia University of Waterloo

April 25, 2013

PIRSA:13040130

Condensed Matter

The discovery of the spin-ice phase in Dy2Ti2O7 numbers among the most significant findings in magnetic materials in over a decade. The spin-ice model is based on an elegant analogy to Pauling’s model of geometrical frustration in water ice, and predicts the same residual entropy, as confirmed by numerous measurements. Melko, den Hertog and Gingras, with numerical work using a loop algorithm to speed up equilibration times, were able to determine an ordering for this system. This had not been seen experimentally observed by several groups. I will present new experimental results for the specific heat of Dy2Ti2O7, demonstrating why previous measurements were unable to correctly capture its low temperature behaviour. By carefully tracking the flow of heat into and out of the material, we observe a non-vanishing specific heat at low temperatures indicating the residual entropy does not actually agree with the Pauling value.

Title	Date	Collection	Type	Info
Gromov-Witten Invariants from 2D Gauge Theories	2013‑04‑30	Quantum Fields and Strings	Scientific Series	View details
From topological insulator to weak scale flavor physics	2013‑04‑30	Particle Physics	Scientific Series	View details
Transporting non-Gaussianity from sub- to super- horizon scales	2013‑04‑30	Cosmology and Gravitation	Scientific Series	View details
Laws of thermodynamics beyond the von Neumann regime	2013‑04‑29	Perimeter Institute Quantum Discussions	Scientific Series	View details
12/13 PSI - Explorations in String Theory Lecture 15	2013‑04‑26	12/13 PSI - Eplorations in String Theory	Course	View details
12/13 PSI - Explorations in Cosmology Lecture 15	2013‑04‑26	12/13 PSI - Explorations in Cosmology	Course	View details
12/13 PSI - Explorations in Condensed Matter Lecture 15	2013‑04‑26	12/13 PSI - Explorations in Condensed Matter	Course	View details
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4	2013‑04‑25	4 Corner Southwest Symposium 2013	Conference	View details
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator	2013‑04‑25	4 Corner Southwest Symposium 2013	Conference	View details
Tensor Networks: an Overview	2013‑04‑25	4 Corner Southwest Symposium 2013	Conference	View details
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7	2013‑04‑25	4 Corner Southwest Symposium 2013	Conference	View details
Absence of Pauling's Residual Entropy in Dy2Ti2O	2013‑04‑25	4 Corner Southwest Symposium 2013	Conference	View details

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Format results

Gromov-Witten Invariants from 2D Gauge Theories

From topological insulator to weak scale flavor physics

Transporting non-Gaussianity from sub- to super- horizon scales

Laws of thermodynamics beyond the von Neumann regime

12/13 PSI - Explorations in String Theory Lecture 15

12/13 PSI - Explorations in Cosmology Lecture 15

12/13 PSI - Explorations in Condensed Matter Lecture 15

Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

Tensor Networks: an Overview

New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Absence of Pauling's Residual Entropy in Dy2Ti2O

Gromov-Witten Invariants from 2D Gauge Theories

From topological insulator to weak scale flavor physics

Transporting non-Gaussianity from sub- to super- horizon scales

Laws of thermodynamics beyond the von Neumann regime

12/13 PSI - Explorations in String Theory Lecture 15

12/13 PSI - Explorations in Cosmology Lecture 15

12/13 PSI - Explorations in Condensed Matter Lecture 15

Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

Tensor Networks: an Overview

New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Absence of Pauling's Residual Entropy in Dy2Ti2O