Talks

10273 - 10284 of 16754 Results

A gauge theory generalization of the fermion-doubling theorem

John McGreevy University of California, San Diego

May 10, 2013

PIRSA:13050050

Quantum Fields and Strings

Condensed Matter
Momentum polarization: an entanglement measure of topological spin and chiral central charge

Xiaoliang Qi Stanford University

May 10, 2013

PIRSA:13050047

Condensed Matter
Twisted Symmetry in Tensor Network States and Topological Order

Oliver Buerschaper Multiverse Computing (Germany)

May 10, 2013

PIRSA:13050048

Quantum Information

Condensed Matter
Defects in Topologically Ordered Quantum Matter

Maissam Barkeshli University of California, Santa Barbara

May 10, 2013

PIRSA:13050053

Condensed Matter
Geometry and the entanglement spectrum in the fractional quantum Hall effect.

May 10, 2013

PIRSA:13050049

Condensed Matter
Topological Phases with of Bosons with Short Range Quantum Entanglement

Ashvin Vishwanath Harvard University

May 10, 2013

PIRSA:13050046

Condensed Matter
Spin-orbital quantum liquid on the honeycomb lattice

Philippe Corboz Universiteit van Amsterdam

May 09, 2013

PIRSA:13050045

Quantum Information

Condensed Matter
Characterizing topological spin liquids using PEPS

Norbert Schuch Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

May 09, 2013

PIRSA:13050044

Quantum Information
The effective field theory of general relativity, running couplings and Asymptotic Safety

John Donoghue University of Massachusetts Amherst

May 09, 2013

PIRSA:13050003

Quantum Gravity
Emergence and Entanglement in Matrix Product States

Frank Verstraete Ghent University

May 09, 2013

PIRSA:13050043

Quantum Information
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Paolo Pani Instituto Superior Tecnico - Departamento de Física

May 09, 2013

PIRSA:13050001

Strong Gravity
Characterizing topological order form a microscopic lattice Hamiltonian

Lukasz Cincio Los Alamos National Laboratory

May 09, 2013

PIRSA:13050042

Quantum Information

Condensed Matter

A gauge theory generalization of the fermion-doubling theorem

John McGreevy University of California, San Diego

May 10, 2013

PIRSA:13050050

Quantum Fields and Strings

Condensed Matter

This talk is about obstructions to symmetry-preserving regulators of quantum field theories in 3+1 dimensions. New examples of such obstructions can be found using the fact that 4+1-dimensional SPT states are characterized by their edge states.
(Based on work in progress with S.M. Kravec.)
Momentum polarization: an entanglement measure of topological spin and chiral central charge

Xiaoliang Qi Stanford University

May 10, 2013

PIRSA:13050047

Condensed Matter

Topologically ordered states are quantum states of matter with topological ground state degeneracy and quasi-particles carrying fractional quantum numbers and fractional statistics. The topological spin is an important property of a topological quasi-particle, which is the Berry phase obtained in the adiabatic self-rotation of the quasi-particle by . For chiral topological states with robust chiral edge states, another fundamental topological property is the edge state chiral central charge . In this paper we propose a new approach to compute the topological spin and chiral central charge in lattice models by defining a new quantity named as the momentum polarization. Momentum polarization is defined on the cylinder geometry as a universal subleading term in the average value of a "partial translation operator". We show that the momentum polarization is a quantum entanglement property which can be computed from the reduced density matrix, and our analytic derivation based on edge conformal field theory shows that the momentum polarization measures the combination of topological spin and central charge. Numerical results are obtained for two example systems, the non-Abelian phase of the honeycomb lattice Kitaev model, and the Laughlin state of a fractional Chern insulator described by a variational Monte Carlo wavefunction. The numerical results verifies the analytic formula with high accuracy, and further suggests that this result remains robust even when the edge states cannot be described by a conformal field theory. Our result provides a new efficient approach to characterize and identify topological states of matter from finite size numerics.
Twisted Symmetry in Tensor Network States and Topological Order

Oliver Buerschaper Multiverse Computing (Germany)

May 10, 2013

PIRSA:13050048

Quantum Information

Condensed Matter
Defects in Topologically Ordered Quantum Matter

Maissam Barkeshli University of California, Santa Barbara

May 10, 2013

PIRSA:13050053

Condensed Matter

I will discuss recent advances in our understanding of extrinsic defects in topologically ordered states. These include line defects, where I will discuss recent developments in the classification of gapped boundaries between Abelian topological states, and various kinds of point defects, which host a rich set of topological physics. The extrinsic point defects provide a new way of realizing topologically protected ground state degeneracies, they carry projective non-abelian statistics even in an Abelian topological state and provide a new path towards universal topological quantum computation, they host a general class of topologically protected "parafermion" zero modes, and they provide an avenue towards distinguishing various symmetry-enriched topological phases. I will discuss several novel physical realizations of such point defects, and also a recent experimental proposal to realize such defects in conventional bilayer fractional quantum Hall systems.
Geometry and the entanglement spectrum in the fractional quantum Hall effect.

May 10, 2013

PIRSA:13050049

Condensed Matter

Fractional quantum hall states with nu = p/q have a characteristic geometry defined by the electric quadrupole moment of the neutral composite boson that is formed by "flux attachment" of q "flux quanta" (guiding-center orbitals) to p charged particles. This characterizes the "Hall viscosity". For FQHE states described by a conformal field theory with a Euclidean metric g_ab, the quadrupole moment is proportional to the "guiding-center spin" of the composite boson and the inverse metric. The geometry gives rise to dipole moments at external edges or internal "orbital entanglement cuts", and can be seen in the entanglement spectrum.
Topological Phases with of Bosons with Short Range Quantum Entanglement

Ashvin Vishwanath Harvard University

May 10, 2013

PIRSA:13050046

Condensed Matter
Spin-orbital quantum liquid on the honeycomb lattice

Philippe Corboz Universiteit van Amsterdam

May 09, 2013

PIRSA:13050045

Quantum Information

Condensed Matter

The symmetric Kugel-Khomskii can be seen as a minimal model describing the interactions between spin and orbital degrees of freedom in certain transition-metal oxides with orbital degeneracy, and it is equivalent to the SU(4) Heisenberg model of four-color fermionic atoms. We present simulation results for this model on various two-dimensional lattices obtained with infinite projected-entangled pair states (iPEPS), an efficient variational tensor-network ansatz for two dimensional wave functions in the thermodynamic limit. We find a rich variety of exotic phases: while on the square and checkerboard lattices the ground state exhibits dimer-N\'eel order and plaquette order, respectively, quantum fluctuations on the honeycomb lattice destroy any order, giving rise to a spin-orbital liquid. Our results are supported from flavor-wave theory and exact diagonalization. Furthermore, the properties of the spin-orbital liquid state on the honeycomb lattice are accurately accounted for by a projected variational wave-function based on the pi-flux state of fermions on the honeycomb lattice at 1/4-filling. In that state, correlations are algebraic because of the presence of a Dirac point at the Fermi level, suggesting that the ground state is an algebraic spin-orbital liquid. This model provides a possible starting point to understand the recently discovered spin-orbital liquid behavior of Ba_3CuSb_2O_9. The present results also suggest to choose optical lattices with honeycomb geometry in the search for quantum liquids in ultra-cold four-color fermionic atoms.
Characterizing topological spin liquids using PEPS

Norbert Schuch Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

May 09, 2013

PIRSA:13050044

Quantum Information

Projected Entangled Pair States (PEPS) provide a local description of correlated many-body states. I will discuss how PEPS can be used to characterize topological spin liquids, in particular Resonating Valence Bond states. On the one hand, I will show how the symmetries in the local PEPS description allow to identify that these states appear as topologically degenerate ground states of local Hamiltonians. On the other hand, I will discuss how from exact diagonalization of the transfer operator one can extract both the topological order and the spin liquid nature of the ground state.
The effective field theory of general relativity, running couplings and Asymptotic Safety

John Donoghue University of Massachusetts Amherst

May 09, 2013

PIRSA:13050003

Quantum Gravity

Effective field theory techniques allow reliable quantum calculations in general relativity at low energy. After a review of these techniques, I will discuss the attempts to define the gravitational corrections to running gauge couplings and to the couplings of gravity itself. I will also describe an attempt to understand the relation between the effective field theory and Asymptotic Safety in the region where they overlap.
Emergence and Entanglement in Matrix Product States

Frank Verstraete Ghent University

May 09, 2013

PIRSA:13050043

Quantum Information
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Paolo Pani Instituto Superior Tecnico - Departamento de Física

May 09, 2013

PIRSA:13050001

Strong Gravity

In the last few years several interesting phenomena associated to the interaction between massive black holes and fundamental bosonic fields have been discovered. I present a selection of them, including superradiance instabilities of spin-0, spin-1 and spin-2 fields, floating orbits in extreme-mass ratio inspirals and black-hole spontaneous scalarization. The theoretical potential of these effects
as almost-model-independent smoking guns for exotic particles and modified gravity, as well as their limitations in realistic astrophysical scenarios, are discussed.
Characterizing topological order form a microscopic lattice Hamiltonian

Lukasz Cincio Los Alamos National Laboratory

May 09, 2013

PIRSA:13050042

Quantum Information

Condensed Matter

In this talk I will show how to obtain a detailed characterization of the emergent topological order starting from microscopic Hamiltonian on a two dimensional lattice. A key step is to obtain a tensor network representation for a complete set of ground states of the Hamiltonian, ﬁrst on an inﬁnite cylinder and then on a ﬁnite torus. As an application of the method I will study lattice Hamiltonians that give rise to selected anyon models, namely chiral semion, Ising as well as Z_3 and Z_5 models.

Title	Date	Collection	Type	Info
A gauge theory generalization of the fermion-doubling theorem	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Momentum polarization: an entanglement measure of topological spin and chiral central charge	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Twisted Symmetry in Tensor Network States and Topological Order	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Defects in Topologically Ordered Quantum Matter	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Geometry and the entanglement spectrum in the fractional quantum Hall effect.	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Topological Phases with of Bosons with Short Range Quantum Entanglement	2013‑05‑10	Emergence & Entanglement II 2013	Conference	View details
Spin-orbital quantum liquid on the honeycomb lattice	2013‑05‑09	Emergence & Entanglement II 2013	Conference	View details
Characterizing topological spin liquids using PEPS	2013‑05‑09	Emergence & Entanglement II 2013	Conference	View details
The effective field theory of general relativity, running couplings and Asymptotic Safety	2013‑05‑09	Quantum Gravity	Scientific Series	View details
Emergence and Entanglement in Matrix Product States	2013‑05‑09	Emergence & Entanglement II 2013	Conference	View details
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes	2013‑05‑09	Strong Gravity	Scientific Series	View details
Characterizing topological order form a microscopic lattice Hamiltonian	2013‑05‑09	Emergence & Entanglement II 2013	Conference	View details

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