Talks

10561 - 10572 of 16754 Results

Looking for spinon deconfinement in two dimensions

Ying Tang Boston College

February 05, 2013

PIRSA:13020127

Condensed Matter
A positive and local formalism for quantum theory

Robert Oeckl Universidad Nacional Autónoma De Mexico (UNAM)

February 05, 2013

PIRSA:13020125

Quantum Foundations
Time Crystals

Alfred Shapere University of Kentucky

February 05, 2013

PIRSA:13020121

Quantum Fields and Strings
Multifield Reheating and the Fate of the Primordial Observables

Ewan Tarrant University of Nottingham

February 05, 2013

PIRSA:13020123

Cosmology
12/13 PSI - Quantum Gravity Review Lecture 7

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 05, 2013

PIRSA:13020048

Quantum Gravity
12/13 PSI - Gravitational Physics Review Lecture 7

Ruth Gregory King's College London

February 05, 2013

PIRSA:13020063

Strong Gravity
12/13 PSI - Condensed Matter Review Lecture 6

Dmitry Abanin

February 04, 2013

PIRSA:13020077

Condensed Matter
12/13 PSI - Quantum Gravity Review Lecture 6

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 04, 2013

PIRSA:13020047

Quantum Gravity
12/13 PSI - Gravitational Physics Review Lecture 6

Ruth Gregory King's College London

February 04, 2013

PIRSA:13020062

Strong Gravity
12/13 PSI - Condensed Matter Review Lecture 5

Alioscia Hamma University of Naples Federico II

February 01, 2013

PIRSA:13020074

Condensed Matter
12/13 PSI - Quantum Gravity Review Lecture 5

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 01, 2013

PIRSA:13020044

Quantum Gravity
A classification of symmetry enriched topological phases with exactly solvable models

Ying Ran Boston College

February 01, 2013

PIRSA:13020122

Condensed Matter

Looking for spinon deconfinement in two dimensions

Ying Tang Boston College

February 05, 2013

PIRSA:13020127

Condensed Matter

We have used a recently proposed quantum Monte Carlo algorithm [1] to study spinons (emergent S = 1/2 excitations) in 2D Resonating-Valence-Bond (RVB) spin liquids and in a J-Q model hosting a Neel – Valence Bond Solid (VBS) phase transition at zero temperature [2]. We confirm that spinons are well defined quasi-particles with finite intrinsic size in the RVB spin liquid. The distance distribution between two spinons shows signatures of deconfinement.
However, at the Neel–VBS transition, we found that the size of a single spinon is significantly greater than the bound-state in VBS, which indicates that spinons are “soft” and shrink when bound state is formed. Both spinon size and confinement length diverge as the critical point is approached. We have also compared spinon statistics in J-Q model with bilayer Heisenberg model and 1D spin chain. We conclude that the spinon deconfinement is marginal in the lowest-energy state in the spin-1 sector, due to very weak attractive spinon interactions. Deconfinement in the vicinity of the critical point should occur at higher energies.
A positive and local formalism for quantum theory

Robert Oeckl Universidad Nacional Autónoma De Mexico (UNAM)

February 05, 2013

PIRSA:13020125

Quantum Foundations

The general boundary formulation (GBF) is an atemporal, but spacetime local formulation of quantum theory. Usually it is presented in terms of the amplitude formalism, which, in the presence of a background time, recovers the pure state formalism of the standard formulation of quantum theory. After reviewing the essentials of the amplitude formalism I will introduce a new "positive formalism", which recovers instead a mixed state formalism. This allows to define general quantum operations within the GBF and opens it to quantum information theory. Moreover, the transition to the positive formalism eliminates operationally irrelevant structure, making the extraction of measurement probabilities more direct. As a consequence, the probability interpretation takes on a remarkably simple and compelling form. I shall describe implications of the positive formalism, both for our understanding of quantum theory and for the practical formulation of quantum theories. I also observe a certain convergence with Lucien Hardy's operator tensor formulation of quantum theory, on which I hope to comment
Time Crystals

Alfred Shapere University of Kentucky

February 05, 2013

PIRSA:13020121

Quantum Fields and Strings

I consider a class of simple classical systems which exhibit motion in their lowest-energy states and thus spontaneously break time-translation symmetry. Their Lagrangians have nonstandard kinetic terms and their Hamiltonians are multivalued functions of momentum, yet they are perfectly consistent and amenable to quantization. Field theoretical generalizations of these systems may have applications in condensed matter physics and cosmology.
Multifield Reheating and the Fate of the Primordial Observables

Ewan Tarrant University of Nottingham

February 05, 2013

PIRSA:13020123

Cosmology

The presence of additional light fields during inflation can source isocurvature fluctuations, which can cause the curvature perturbation $\zeta$, and its statistics to evolve on superhorizon scales. I will demonstrate that if these fluctuations have not completely decayed before the onset of perturbative reheating, then primordial observables such as the level of non--Gaussianity can develop substantial reheating dependant corrections. I will argue that for inflationary models where an adiabatic condition is not reached before the relevant fields begin to decay, we must be careful in our interpretation of any observational constraints that place bounds on the statistics of $\zeta$.
12/13 PSI - Quantum Gravity Review Lecture 7

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 05, 2013

PIRSA:13020048

Quantum Gravity
12/13 PSI - Gravitational Physics Review Lecture 7

Ruth Gregory King's College London

February 05, 2013

PIRSA:13020063

Strong Gravity
12/13 PSI - Condensed Matter Review Lecture 6

Dmitry Abanin

February 04, 2013

PIRSA:13020077

Condensed Matter
12/13 PSI - Quantum Gravity Review Lecture 6

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 04, 2013

PIRSA:13020047

Quantum Gravity
12/13 PSI - Gravitational Physics Review Lecture 6

Ruth Gregory King's College London

February 04, 2013

PIRSA:13020062

Strong Gravity
12/13 PSI - Condensed Matter Review Lecture 5

Alioscia Hamma University of Naples Federico II

February 01, 2013

PIRSA:13020074

Condensed Matter
12/13 PSI - Quantum Gravity Review Lecture 5

Bianca Dittrich Perimeter Institute for Theoretical Physics

February 01, 2013

PIRSA:13020044

Quantum Gravity
A classification of symmetry enriched topological phases with exactly solvable models

Ying Ran Boston College

February 01, 2013

PIRSA:13020122

Condensed Matter

Two types of topological phases have attracted a lot of attention in condensed matter physics: symmetry protected topological(SPT) phases and topologically ordered phases. On the one hand, SPT phases are protected by given global symmetries while there is no topological order in the bulk. On the other hand, topologically ordered phases do not require symmetry and feature topological ground state degeneracy. In this talk, I present a classification of phases with both topological orders and global symmetries, equipped with local bosonic exactly solvable models. This classification, in some sense, organizes previous pieces of understandings on SPT phases, topological orders, symmetry fractionalizations, into a single framework. Solution of the exactly solvable models and measurable consequences will be discussed.

Title	Date	Collection	Type	Info
Looking for spinon deconfinement in two dimensions	2013‑02‑05	Quantum Matter	Scientific Series	View details
A positive and local formalism for quantum theory	2013‑02‑05	Quantum Foundations	Scientific Series	View details
Time Crystals	2013‑02‑05	Quantum Fields and Strings	Scientific Series	View details
Multifield Reheating and the Fate of the Primordial Observables	2013‑02‑05	Cosmology and Gravitation	Scientific Series	View details
12/13 PSI - Quantum Gravity Review Lecture 7	2013‑02‑05	12/13 PSI - Quantum Gravity Review	Course	View details
12/13 PSI - Gravitational Physics Review Lecture 7	2013‑02‑05	12/13 PSI - Gravitational Physics Review	Course	View details
12/13 PSI - Condensed Matter Review Lecture 6	2013‑02‑04	12/13 PSI - Condensed Matter Review	Course	View details
12/13 PSI - Quantum Gravity Review Lecture 6	2013‑02‑04	12/13 PSI - Quantum Gravity Review	Course	View details
12/13 PSI - Gravitational Physics Review Lecture 6	2013‑02‑04	12/13 PSI - Gravitational Physics Review	Course	View details
12/13 PSI - Condensed Matter Review Lecture 5	2013‑02‑01	12/13 PSI - Condensed Matter Review	Course	View details
12/13 PSI - Quantum Gravity Review Lecture 5	2013‑02‑01	12/13 PSI - Quantum Gravity Review	Course	View details
A classification of symmetry enriched topological phases with exactly solvable models	2013‑02‑01	Quantum Matter	Scientific Series	View details

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