Talks

11965 - 11976 of 20132 Results

Geometrical dependence of information in 2d critical systems

Paul Fendley University of Oxford

February 12, 2014

PIRSA:14020119
13/14 PSI - String Theory Review - Lecture 12

Davide Gaiotto Perimeter Institute for Theoretical Physics

February 12, 2014

PIRSA:14020032
Many-body localization: Local integrals of motion, area-law entanglement, and quantum dynamics

Dmitry Abanin Princeton University

February 12, 2014

PIRSA:14020127
Geometry of topological matter: some examples

Duncan Haldane Princeton University

February 12, 2014

PIRSA:14020117
13/14 PSI - Condensed Matter Review - Lecture 12

Alioscia Hamma University of Naples Federico II

February 12, 2014

PIRSA:14020105
Fractional Quantum Hall Effect in a curved space

Pavel Wiegmann

February 11, 2014

PIRSA:14020112
13/14 PSI - Cosmology Review - Lecture 10

Latham Boyle University of Edinburgh

February 11, 2014

PIRSA:14020018
Tuning magnetism and Chern bands in spin-orbit coupled double perovskites

Arun Paramekanti University of Toronto

February 11, 2014

PIRSA:14020116
Our Lopsided Universe

Marina Cortes Institute for Astrophysics and Space Sciences

February 11, 2014

PIRSA:14020139

Astrophysics
13/14 PSI - String Theory Review - Lecture 11

Davide Gaiotto Perimeter Institute for Theoretical Physics

February 11, 2014

PIRSA:14020031
Topological response in gapless systems: from Weyl semimetals to metallic ferromagnets

Anton Burkov University of Waterloo

February 11, 2014

PIRSA:14020115
Specific heat and ac susceptibility measurements on the Spin Ice, Dy2Ti2O7

Jan Kycia University of Waterloo

February 11, 2014

PIRSA:14020114

Geometrical dependence of information in 2d critical systems

Paul Fendley University of Oxford

February 12, 2014

PIRSA:14020119

In both classical and quantum critical systems, universal contributions to the mutual information and Renyi entropy depend on geometry. I will first explain how in 2d classical critical systems on a rectangle, the mutual information depends on the central charge in a fashion making its numerical extraction easy, as in 1d quantum systems. I then describe analogous results for 2d quantum critical systems. Specifically, in special 2d quantum systems such as quantum dimer/Lifshitz models, the leading geometry-dependent term in the Renyi entropies can be computed exactly. In more common 2d quantum systems, numerical computations of a corner term hint toward the existence of a universal quantity providing a measure of the number of degrees of freedom analogous to the central charge.
13/14 PSI - String Theory Review - Lecture 12

Davide Gaiotto Perimeter Institute for Theoretical Physics

February 12, 2014

PIRSA:14020032
Many-body localization: Local integrals of motion, area-law entanglement, and quantum dynamics

Dmitry Abanin Princeton University

February 12, 2014

PIRSA:14020127

We demonstrate that the many-body localized phase is characterized by the existence of infinitely many local conservation laws. We argue that many-body eigenstates can be obtained from product states by a sequence of nearly local unitary transformation, and therefore have an area-law entanglement entropy, typical of ground states. Using this property, we construct the local integrals of motion in terms of projectors onto certain linear combinations of eigenstates [1]. The local integrals of motion can be viewed as effective quantum bits which have a conserved z-component that cannot decay. Thus, the dynamics is reduced to slow dephasing between distant effective bits. For initial product states, this leads to a characteristic slow power-law decay of local observables, which is measurable experimentally, as well as to logarithmic in time growth of entanglement entropy [2,3]. We support our findings by numerical simulations of random-field XXZ spin chains. Our work shows that the many-body localized phase is locally integrable, reveals a simple entanglement structure of eigenstates, and establishes the laws of dynamics in this phase.

[1] M. Serbyn, Z. Papic, D. A. Abanin, Phys. Rev. Lett. 111, 127201 (2013).
[2] Jens H. Bardarson, Frank Pollmann, and Joel E. Moore, Phys. Rev. Lett. 109, 017202 (2012).
[3] M. Serbyn, Z. Papic, D. A. Abanin, Phys. Rev. Lett. 110, 260601 (2013)
Geometry of topological matter: some examples

Duncan Haldane Princeton University

February 12, 2014

PIRSA:14020117

I will look at two cases of the interplay of geometry (curvature) and topology:
(1) 3D Topological metals: how to understand their surface "Fermi arcs" in terms of their emergent conservation laws and the Streda formula for the non-quantized anomalous Hall effect.
(2) The Hall viscosity tensor in the FQHE as a local field, and its Gaussian-curvature response that allows local compression or expansion of the fluid to accommodate substrate inhomogeneity.
13/14 PSI - Condensed Matter Review - Lecture 12

Alioscia Hamma University of Naples Federico II

February 12, 2014

PIRSA:14020105
Fractional Quantum Hall Effect in a curved space

Pavel Wiegmann

February 11, 2014

PIRSA:14020112

We developed a general method to compute the correlation functions of FQH states on a curved space. The computation features the gravitational trace anomaly and reveals geometric properties of FQHE. Also we highlight a relation between the gravitational and electromagnetic response functions. The talk is based on the recent paper with T. Can and M. Laskin.
13/14 PSI - Cosmology Review - Lecture 10

Latham Boyle University of Edinburgh

February 11, 2014

PIRSA:14020018
Tuning magnetism and Chern bands in spin-orbit coupled double perovskites

Arun Paramekanti University of Toronto

February 11, 2014

PIRSA:14020116

We show that double perovskites with 3d and 5d transition metal ions exhibit spin-orbit coupled magnetic excitations, finding good agreement with neutron scattering experiments in bulk powder samples. Motivated by experimental developments in the field of oxide heterostructures, we also study double perovskites films grown along the [111] direction. We show that spin-orbit coupling in such low dimensional systems can drive ferromagnetic order due to electronic correlations. This results in topological Chern bands, with symmetry-allowed trigonal deformations leading to quantum anomalous Hall states supporting a pair of chiral edge modes.
Our Lopsided Universe

Marina Cortes Institute for Astrophysics and Space Sciences

February 11, 2014

PIRSA:14020139

Astrophysics

After a short introduction to open inflation and the observed large-scale cosmic microwave anomalies, which have been confirmed by the Planck satellite, I'll argue that the anomalies are naturally explained in the context of a marginally-open, negatively curved universe. I'll look in particular at the dipole power asymmetry, and motivate that this asymmetry can happen if our universe has bubble nucleated in a phase transition during a period of early inflation, and, as a result, has open geometry. Open inflation models, which are motivated by the string landscape and can excite `super-curvature' perturbation modes, can explain the presence of a very-large-scale perturbation, like the one we observe, which leads to a dipole modulation of the power spectrum. I'll provide a specific implementation of the scenario which is compatible with all existing constraints.
13/14 PSI - String Theory Review - Lecture 11

Davide Gaiotto Perimeter Institute for Theoretical Physics

February 11, 2014

PIRSA:14020031
Topological response in gapless systems: from Weyl semimetals to metallic ferromagnets

Anton Burkov University of Waterloo

February 11, 2014

PIRSA:14020115

Standard picture of a topologically-nontrivial phase of matter is an insulator with a bulk energy gap, but metallic surface states, protected by the bulk gap. Recent work has shown, however, that certain gapless systems may also be topologically nontrivial, in a precise and experimentally observable way. In this talk I will review our work on a class of such systems, in which the nontrivial topological properties arise from the existence of nondegenerate point band-touching nodes (Weyl nodes) in their electronic structure. Weyl nodes generally exist in any three-dimensional material with a broken time-reversal or inversion symmetry. Their effect is particularly striking, however, when the nodes coincide with the Fermi energy and no other states at the Fermi energy exist. Such "Weyl semimetals" have vanishing bulk density of states, but have gapless metallic surface states with an open (unlike in a regular two-dimensional metal) Fermi surface ("Fermi arc"). I will discuss our proposal to realize Weyl semimetal state in a heterostructure, consisting of alternating layers of topological and ordinary insulator, doped with magnetic impurities. I will further show that, apart from Weyl semimetals, even such "ordinary" materials as common metallic ferromagnets, in fact also possess Weyl nodes in the electronic structure, leading to the appearance of chiral Fermi-arc surface states and the corresponding contribution to their intrinsic anomalous Hall conductivity.
Specific heat and ac susceptibility measurements on the Spin Ice, Dy2Ti2O7

Jan Kycia University of Waterloo

February 11, 2014

PIRSA:14020114

Some time ago (1999), Dy2Ti2O7, was shown to be a magnetic analog of water ice, and thus dubbed "spin ice". Recently, theories and experiments have developed the perspective of viewing excitations within the low temperature phase of this spin ice as monopoles. I will present early results of specific heat, ac susceptibility and magnetization measurements as well as my group's recent results on this system

Title	Date	Collection	Type	Info
Geometrical dependence of information in 2d critical systems	2014‑02‑12	Emergence in Complex Systems	Conference	View details
13/14 PSI - String Theory Review - Lecture 12	2014‑02‑12	13/14 PSI - String Theory Review	Course	View details
Many-body localization: Local integrals of motion, area-law entanglement, and quantum dynamics	2014‑02‑12	Emergence in Complex Systems	Conference	View details
Geometry of topological matter: some examples	2014‑02‑12	Emergence in Complex Systems	Conference	View details
13/14 PSI - Condensed Matter Review - Lecture 12	2014‑02‑12	13/14 PSI - Condensed Matter Review	Course	View details
Fractional Quantum Hall Effect in a curved space	2014‑02‑11	Emergence in Complex Systems	Conference	View details
13/14 PSI - Cosmology Review - Lecture 10	2014‑02‑11	13/14 PSI - Cosmology Review	Course	View details
Tuning magnetism and Chern bands in spin-orbit coupled double perovskites	2014‑02‑11	Emergence in Complex Systems	Conference	View details
Our Lopsided Universe	2014‑02‑11	Cosmology and Gravitation	Scientific Series	View details
13/14 PSI - String Theory Review - Lecture 11	2014‑02‑11	13/14 PSI - String Theory Review	Course	View details
Topological response in gapless systems: from Weyl semimetals to metallic ferromagnets	2014‑02‑11	Emergence in Complex Systems	Conference	View details
Specific heat and ac susceptibility measurements on the Spin Ice, Dy2Ti2O7	2014‑02‑11	Emergence in Complex Systems	Conference	View details

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Format results

Geometrical dependence of information in 2d critical systems

13/14 PSI - String Theory Review - Lecture 12

Many-body localization: Local integrals of motion, area-law entanglement, and quantum dynamics

Geometry of topological matter: some examples

13/14 PSI - Condensed Matter Review - Lecture 12

Fractional Quantum Hall Effect in a curved space

13/14 PSI - Cosmology Review - Lecture 10

Tuning magnetism and Chern bands in spin-orbit coupled double perovskites

Our Lopsided Universe

13/14 PSI - String Theory Review - Lecture 11

Topological response in gapless systems: from Weyl semimetals to metallic ferromagnets

Specific heat and ac susceptibility measurements on the Spin Ice, Dy2Ti2O7

Geometrical dependence of information in 2d critical systems

13/14 PSI - String Theory Review - Lecture 12

Many-body localization: Local integrals of motion, area-law entanglement, and quantum dynamics

Geometry of topological matter: some examples

13/14 PSI - Condensed Matter Review - Lecture 12

Fractional Quantum Hall Effect in a curved space

13/14 PSI - Cosmology Review - Lecture 10

Tuning magnetism and Chern bands in spin-orbit coupled double perovskites

Our Lopsided Universe

13/14 PSI - String Theory Review - Lecture 11

Topological response in gapless systems: from Weyl semimetals to metallic ferromagnets

Specific heat and ac susceptibility measurements on the Spin Ice, Dy2Ti2O7