Condensed Matter

Displaying 1081 - 1092 of 1258

Classifying fractionalization: symmetry classification of gapped Z2 spin liquids in two dimensions

Michael Hermele University of Colorado Boulder
March 26, 2013

PIRSA:13030116
Condensed Matter
Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
Gravitational anomaly and topological phases

Shinsei Ryu University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
A K matrix construction of symmetry enriched phases
February 20, 2013

PIRSA:13020140
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 14

Dmitry Abanin
February 15, 2013

PIRSA:13020088
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 13

Dmitry Abanin
February 14, 2013

PIRSA:13020087
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 12

Dmitry Abanin
February 13, 2013

PIRSA:13020086
Condensed Matter
Fractional Quantum Hall States on an infinite cylinder: characterizing topological order and quasiparticle forces using infinite DMRG.

Michael Zaletel University of California, Berkeley
February 12, 2013

PIRSA:13020129
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 11

Dmitry Abanin
February 12, 2013

PIRSA:13020085
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 10

Dmitry Abanin
February 11, 2013

PIRSA:13020081
Condensed Matter

Classifying fractionalization: symmetry classification of gapped Z2 spin liquids in two dimensions

Michael Hermele University of Colorado Boulder
March 26, 2013

PIRSA:13030116
Condensed Matter
Quantum number fractionalization is a remarkable property of topologically ordered states of matter, such as fractional quantum Hall liquids, and quantum spin liquids. For a given type of topological order, there are generally many ways to fractionalize the quantum numbers of a given symmetry. What does it mean to have different types of fractionalization? Are different types of fractionalization a universal property that can be used to distinguish phases of matter? In this talk, I will answer these questions, focusing on a simple class of topologically ordered phases, namely two-dimensional gapped Z2 spin liquids, and I will present a symmetry classification of these phases. I will also discuss efforts in progress to find microscopic models realizing different symmetry classes.
Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
A quantum spin liquid is a solid whose atoms have magnetic moments but, because of quantum fluctuations, these moments fluctuate like a liquid even at zero temperature. Two dimensional spin liquids have been suggested as a way to produce high temperature superconductivity, and to build quantum computers. Just as helium is the only element which is a liquid at zero temperature, 2D spin liquids have been extremely difficult to find, despite decades of effort, raising the question, do realistic spin liquids even exist?
Recently, apparent spin liquids have been found experimentally, stimulating theoretical work to find simple model Hamiltonians of frustrated spin systems that have spin liquid ground states.

In this talk, I will give a broad overview of spin liquids and then focus on our simulations of the kagome Heisenberg model, a simple, realistic model of some of the recent experimental spin liquids, where we find a spin liquid ground state.
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
In this talk we will discuss both the one-photon and two-photon switching mechanisms in hybrid nanomaterials made from two or more semiconductor, metallic and optical nanostructures. The most prominent examples of these nanostructures are graphene, semiconductor quantum dots, metallic nanoparticles, and photonic and polaritonic crystals. Advances in nanoscience have allowed for the construction of these new classes of hybrid nanomaterials. Optical excitations in semiconductor nanostructures are electron-hole pairs (excitons) whereas excitations in metallic nanostructures are surface plasmons which are collective oscillations of electrons. Therefore, the combination of these systems can provide attractive opportunities to modify, design and control optical properties and to observe new phenomena which are based on exciton-plasmon interactions. It is expected that this research will provide a theoretical road map for the development of optical sensing and optical switching.
Gravitational anomaly and topological phases

Shinsei Ryu University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
Since the quantum Hall effect, the notion of topological phases of matter has been extended to those that are well-defined (or: ``protected'') in the presence of a certain set of symmetries, and that exist in dimensions higher than two. In the (fractional) quantum Hall effects (and in ``chiral'' topological phases in general), Laughlin's thought experiment provides a key insight into their topological characterization; it shows a close connection between topological phases and quantum anomalies. By taking various examples, I will demonstrate that quantum anomalies serve as a useful tool to diagnose (and even define) topological properties of the systems. For chiral topological phases in (2+1) dimensions and (3+1) dimensional topological superconductors, I will discuss topological responses of the system which involve a cross correlation between thermal transport, angular momentum, and entropy. We also argue that gravitational anomaly is useful to study symmetry protected topological phases in (2+1) dimensions.
DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
I will present a density-matrix renormalization group (DMRG) study of the S=1/2 Heisenberg antiferromagnet on the kagome lattice to identify the conjectured spin liquid ground state. Exploiting SU(2) spin symmetry, which allows us to keep up to 16,000 DMRG states, we consider cylinders with circumferences up to 17 lattice spacings and find a spin liquid ground state with an estimated per site energy of -0.4386(5), a spin gap of 0.13(1), very short-range decay in spin, dimer and chiral correlation functions and finite topological entanglement consistent with the logarithm of 2, ruling out gapless, chiral or non-topological spin liquids. All this would provide strong evidence for a gapped topological Z_2 spin liquid.
A K matrix construction of symmetry enriched phases
February 20, 2013

PIRSA:13020140
Condensed Matter
We construct in the K matrix formalism concrete examples of symmetry enriched topological phases, namely intrinsically topological phases with global symmetries. We focus on the Abelian and non-chiral topological phases and demonstrate by our examples how the interplay between the global symmetry and the fusion algebra of the anyons of a topologically ordered system determines the existence of gapless edge modes protected by the symmetry and that a (quasi)-group structure can be defined among these phases. Our examples include phases that display charge fractionalization and more exotic non-local anyon exchange under global symmetry that correspond to general group extensions of the global symmetry group.
12/13 PSI - Condensed Matter Review Lecture 14

Dmitry Abanin
February 15, 2013

PIRSA:13020088
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 13

Dmitry Abanin
February 14, 2013

PIRSA:13020087
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 12

Dmitry Abanin
February 13, 2013

PIRSA:13020086
Condensed Matter
Fractional Quantum Hall States on an infinite cylinder: characterizing topological order and quasiparticle forces using infinite DMRG.

Michael Zaletel University of California, Berkeley
February 12, 2013

PIRSA:13020129
Condensed Matter
The density matrix renormalization group (DMRG), which has proved so successful in one dimension, has been making the push into higher dimensions, with the fractional quantum Hall (FQH) effect an important target. I'll briefly explain how the infinite DMRG algorithm can be adapted to find the degenerate ground states of a microscopic FQH Hamiltonian on an infinitely long cylinder, then focus on two applications. To characterize the topological order of the phase, I'll show that the bipartite entanglement spectrum of the ground state is sufficient to determine the quasiparticle charges, topological spins, quantum dimensions, chiral central charge, and Hall viscosity of the phase. Then I will show how to introduce localized quasiparticles of fixed topological charge. By pinning a pair of quasiparticles and dragging them into contact, we can directly measure the force curve of their interaction.
12/13 PSI - Condensed Matter Review Lecture 11

Dmitry Abanin
February 12, 2013

PIRSA:13020085
Condensed Matter
12/13 PSI - Condensed Matter Review Lecture 10

Dmitry Abanin
February 11, 2013

PIRSA:13020081
Condensed Matter

Title	Speaker(s)	Date	Talk Type	Info link
Classifying fractionalization: symmetry classification of gapped Z2 spin liquids in two dimensions	Michael Hermele	2013-03-26	Scientific Series	View details
Frustrated Magnets and Quantum Spin Liquids	Steven White	2013-03-20	Scientific Series	View details
One-photon and two-photon switching in graphene and optical nanomaterials	Mahi Singh	2013-03-08	Scientific Series	View details
Gravitational anomaly and topological phases	Shinsei Ryu	2013-02-28	Scientific Series	View details
DMRG Studies on the Spin Liquid Ground State of the Kagome Model	Stefan Depenbrock	2013-02-26	Scientific Series	View details
A K matrix construction of symmetry enriched phases		2013-02-20	Scientific Series	View details
12/13 PSI - Condensed Matter Review Lecture 14	Dmitry Abanin	2013-02-15	Course	View details
12/13 PSI - Condensed Matter Review Lecture 13	Dmitry Abanin	2013-02-14	Course	View details
12/13 PSI - Condensed Matter Review Lecture 12	Dmitry Abanin	2013-02-13	Course	View details
Fractional Quantum Hall States on an infinite cylinder: characterizing topological order and quasiparticle forces using infinite DMRG.	Michael Zaletel	2013-02-12	Scientific Series	View details
12/13 PSI - Condensed Matter Review Lecture 11	Dmitry Abanin	2013-02-12	Course	View details
12/13 PSI - Condensed Matter Review Lecture 10	Dmitry Abanin	2013-02-11	Course	View details

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Classifying fractionalization: symmetry classification of gapped Z2 spin liquids in two dimensions

Frustrated Magnets and Quantum Spin Liquids

One-photon and two-photon switching in graphene and optical nanomaterials

Gravitational anomaly and topological phases

DMRG Studies on the Spin Liquid Ground State of the Kagome Model

A K matrix construction of symmetry enriched phases

12/13 PSI - Condensed Matter Review Lecture 14

12/13 PSI - Condensed Matter Review Lecture 13

12/13 PSI - Condensed Matter Review Lecture 12

Fractional Quantum Hall States on an infinite cylinder: characterizing topological order and quasiparticle forces using infinite DMRG.

12/13 PSI - Condensed Matter Review Lecture 11

12/13 PSI - Condensed Matter Review Lecture 10

Classifying fractionalization: symmetry classification of gapped Z2 spin liquids in two dimensions

Frustrated Magnets and Quantum Spin Liquids

One-photon and two-photon switching in graphene and optical nanomaterials

Gravitational anomaly and topological phases

DMRG Studies on the Spin Liquid Ground State of the Kagome Model

A K matrix construction of symmetry enriched phases

12/13 PSI - Condensed Matter Review Lecture 14

12/13 PSI - Condensed Matter Review Lecture 13

12/13 PSI - Condensed Matter Review Lecture 12

Fractional Quantum Hall States on an infinite cylinder: characterizing topological order and quasiparticle forces using infinite DMRG.

12/13 PSI - Condensed Matter Review Lecture 11

12/13 PSI - Condensed Matter Review Lecture 10