Scientific Series

Displaying 3037 - 3048 of 5007

Self-assembling tensor networks and holography in disordered spin chains

Andrew Goldsborough RWTH Aachen University
September 16, 2014

PIRSA:14090029
Condensed Matter
Infinite Chiral Symmetry in Four Dimensions

Wolfger Peelaers University of Oxford

September 16, 2014

PIRSA:14090079
Scalar Simplified Models and Dark Matter at Colliders

Matthew Buckley Rutgers University
September 16, 2014

PIRSA:14090080
High Energy Physics
Cosmic flows: testing gravity and the matter power spectrum on very large scales

Mike Hudson University of Waterloo
September 16, 2014

PIRSA:14090077
Astrophysics
Maximal supergravity, holography and the Romans mass

Oscar Varela Harvard University
September 12, 2014

PIRSA:14090071
High Energy Physics
Stripes and pairing in t-J and Hubbard models

Steven White University of California, Irvine
September 11, 2014

PIRSA:14090074
Condensed Matter
Force-Free Electrodynamics around Extreme Kerr Black Holes

Maria J. Rodriguez Utah State University
September 11, 2014

PIRSA:14090065
General Relativity & Quantum Cosmology
An invariant of topologically ordered states under local unitary transformations

Jeongwan Haah Massachusetts Institute of Technology (MIT) - Department of Physics
September 10, 2014

PIRSA:14090030
Quantum Physics
Short-Range Entangled Phases and Topology

Anton Kapustin California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy

September 10, 2014

PIRSA:14090002
Many-Body Localization in translation invariant systems?

Francois Huveneers University of Paris-Saclay

September 09, 2014

PIRSA:14090027
Firewalls- A GR perspective

Bill Unruh University of British Columbia
September 04, 2014

PIRSA:14090066
General Relativity & Quantum Cosmology
Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter

Self-assembling tensor networks and holography in disordered spin chains

Andrew Goldsborough RWTH Aachen University
September 16, 2014

PIRSA:14090029
Condensed Matter
We show that the numerical strong disorder renormalization group algorithm (SDRG) of Hikihara et.\ al.\ [{Phys. Rev. B} {\bf 60}, 12116 (1999)] for the one-dimensional disordered Heisenberg model naturally describes a tree tensor network (TTN) with an irregular structure defined by the strength of the couplings. Employing the holographic interpretation of the TTN in Hilbert space, we compute expectation values, correlation functions and the entanglement entropy using the geometrical properties of the TTN. We find that the disorder averaged spin-spin correlation scales with the average path length through the tensor network while the entanglement entropy scales with the minimal surface connecting two regions. Furthermore, the entanglement entropy increases with both disorder and system size, resulting in an area-law violation. Our results demonstrate the usefulness of a self-assembling TTN approach to disordered systems and quantitatively validate the connection between holography and quantum many-body systems.
Infinite Chiral Symmetry in Four Dimensions

Wolfger Peelaers University of Oxford

September 16, 2014

PIRSA:14090079

We describe a new correspondence between four-dimensional conformal field theories with extended supersymmetry and two-dimensional chiral algebras. We explore the resulting chiral algebras in the context of theories of class S. The class S duality web implies nontrivial associativity properties for the corresponding chiral algebras, the structure of which can be summarized by a generalized topological quantum field theory.
Scalar Simplified Models and Dark Matter at Colliders

Matthew Buckley Rutgers University
September 16, 2014

PIRSA:14090080
High Energy Physics
Dark matter is clear evidence of the existence of new physics beyond the Standard Model, and there are compelling reasons to expect that this physics can be probed at the LHC. As we prepare for Run II, we must consider a wide range of possible phenomenology, leaving no stone unturned. In this talk, I present a set of scalar and pseudoscalar models which provide a useful framework to interpret dark matter results, and can motivate new searches in novel channels at the LHC.
Cosmic flows: testing gravity and the matter power spectrum on very large scales

Mike Hudson University of Waterloo
September 16, 2014

PIRSA:14090077
Astrophysics
Peculiar velocities - deviations from Hubble expansion - are the only practical probe of the growth of matter density fluctuations on very large scales in the nearby Universe. I will discuss recent measurements of quantities of cosmological interest from our group and others. One is the "bulk" flow of nearby galaxies with respect to the frame defined by the Cosmic Microwave Background, and what this tells us about fluctuations on large very spatial scales. The second is the measurement of the growth rate of fluctuations, a critical test of Lambda CDM and modified gravity models.
Maximal supergravity, holography and the Romans mass

Oscar Varela Harvard University
September 12, 2014

PIRSA:14090071
High Energy Physics
At large N, an important sector of the ABJM field theory defined on a stack of N M2-branes can be described holographically by the D=4 N=8 SO(8)-gauged supergravity of de Wit and Nicolai. Since its inception, the latter has been tacitly assumed to be unique. Recently, however, a one-parameter family of SO(8) gaugings of N=8 supergravity has been discovered, the de Wit-Nicolai theory being just a member in this class. I will explain how this overlooked family of SO(8)-gauged supergravities is deeply related to electric/magnetic duality breaking in four dimensions. I will then discuss some predictions that can be made about the family of dual large-N field theories that these supergravities define, focusing on the structure of superconformal phases and the RG flows between them. I will finally argue that when the gauging is chosen to be related, but different, to the SO(8) one, the D=4 N=8 family arises as consistent truncation of massive IIA on the six-sphere, with the Romans mass identified as the electric/magnetic duality-breaking parameter.
Stripes and pairing in t-J and Hubbard models

Steven White University of California, Irvine
September 11, 2014

PIRSA:14090074
Condensed Matter
This has been a leading question in condensed matter physics since the discovery of the cuprate superconductors. In this talk I will review some of the DMRG and tensor network results for the ground states of these models. A key question I'll address is the issue of stripes: are the ground states striped? Do stripes compete with or induce d-wave superconductivity? Another question I'll address is: how well does 2D DMRG do in comparison with iPEPS and quantum Monte Carlo. I will also show recent results for a standard 3-band Hubbard model for the cuprates. The asymmetry between hole and electron doped systems which is seen in the cuprates arises naturally from this model.
Force-Free Electrodynamics around Extreme Kerr Black Holes

Maria J. Rodriguez Utah State University
September 11, 2014

PIRSA:14090065
General Relativity & Quantum Cosmology
Plasma-filled magnetospheres can extract energy from a spinning black hole and provide the power source for a variety of observed astrophysical phenomena. These magnetospheres are described by the highly nonlinear equations of force-free electrodynamics, or FFE. Typically these equations can only be solved numerically. In this talk I will explain how to analytically obtain several infinite families of exact solutions of the full nonlinear FFE equations very near the horizon of a maximally spinning black hole, where the energy extraction takes place.
An invariant of topologically ordered states under local unitary transformations

Jeongwan Haah Massachusetts Institute of Technology (MIT) - Department of Physics
September 10, 2014

PIRSA:14090030
Quantum Physics
For an anyon model in two spatial dimensions described by a modular tensor category, the topological S-matrix encodes the mutual braiding statistics, the quantum dimensions, and the fusion rules of anyons. It is nontrivial whether one can compute the topological S-matrix from a single ground state wave function. In this talk, I will show that, for a class of Hamiltonians, it is possible to define the S-matrix regardless of the degeneracy of the ground state. The definition manifests invariance of the S-matrix under local unitary transformations (quantum circuits). The defined S-matrix depends only on the ground state, in the sense that it can be computed by any Hamiltonian in the class of which the state is a ground state. This property, together with the local unitary invariance implies that any quantum circuit that connects two ground states of distinct topological S-matrices must have depth that is at least linear in the diameter of the system. A higher dimensional analog is straightforward. [arXiv:1407.2926]
Short-Range Entangled Phases and Topology

Anton Kapustin California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy

September 10, 2014

PIRSA:14090002

Recently a new and rather unexpected connection between condensed matter physics and algebraic topology has been noted. Namely, it appears that phases of matter with an energy gap, no long-range entanglement, and fixed symmetry can be classified using cobordism theory. I will exhibit several examples of this connection and describe a possible explanation.
Many-Body Localization in translation invariant systems?

Francois Huveneers University of Paris-Saclay

September 09, 2014

PIRSA:14090027

Roughly speaking, Many-Body Localization (MBL) refers to the state of a material that fails to thermalize. Though MBL has mostly been studied in quenched disordered systems, several authors have recently proposed that this phase could be realized in clean (translation invariant) systems too. In this talk, I will discuss this idea and ask to which extent an MBL phase can indeed be expected in systems without quenched disorder. Hopefully, the discussion shed also some light on the localization-delocalization transition for more generic many-body systems. From joint work with W. De Roeck (Leuven), M. Mueller (Trieste), M. Schiulaz (Trieste).
Firewalls- A GR perspective

Bill Unruh University of British Columbia
September 04, 2014

PIRSA:14090066
General Relativity & Quantum Cosmology
This talk will examine the Firewall argument and a number of possible approaches to it, with a variety of simple examples to try to clarify various aspects of the arguments.
Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter
We consider rather general spin-1/2 lattices with large coordination numbers Z.
Based on the monogamy of entanglement and other properties of the concurrence C,
we derive rigorous bounds for the entanglement between neighboring spins,
which show that C decreases for large Z. In addition, the concurrence C measures the deviation from mean-field behavior and can only vanish if the mean-field ansatz yields an exact ground state of the Hamiltonian. Motivated by these findings, we propose an improved mean-field ansatz by adding entanglement

Title	Speaker(s)	Date	Talk Type	Info link
Self-assembling tensor networks and holography in disordered spin chains	Andrew Goldsborough	2014-09-16	Scientific Series	View details
Infinite Chiral Symmetry in Four Dimensions	Wolfger Peelaers	2014-09-16	Scientific Series	View details
Scalar Simplified Models and Dark Matter at Colliders	Matthew Buckley	2014-09-16	Scientific Series	View details
Cosmic flows: testing gravity and the matter power spectrum on very large scales	Mike Hudson	2014-09-16	Scientific Series	View details
Maximal supergravity, holography and the Romans mass	Oscar Varela	2014-09-12	Scientific Series	View details
Stripes and pairing in t-J and Hubbard models	Steven White	2014-09-11	Scientific Series	View details
Force-Free Electrodynamics around Extreme Kerr Black Holes	Maria J. Rodriguez	2014-09-11	Scientific Series	View details
An invariant of topologically ordered states under local unitary transformations	Jeongwan Haah	2014-09-10	Scientific Series	View details
Short-Range Entangled Phases and Topology	Anton Kapustin	2014-09-10	Scientific Series	View details
Many-Body Localization in translation invariant systems?	Francois Huveneers	2014-09-09	Scientific Series	View details
Firewalls- A GR perspective	Bill Unruh	2014-09-04	Scientific Series	View details
Monogamy of entanglement and improved mean-field ansatz for spin lattices	Ralf Schuetzhold	2014-09-02	Scientific Series	View details

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Format results

Self-assembling tensor networks and holography in disordered spin chains

Infinite Chiral Symmetry in Four Dimensions

Scalar Simplified Models and Dark Matter at Colliders

Cosmic flows: testing gravity and the matter power spectrum on very large scales

Maximal supergravity, holography and the Romans mass

Stripes and pairing in t-J and Hubbard models

Force-Free Electrodynamics around Extreme Kerr Black Holes

An invariant of topologically ordered states under local unitary transformations

Short-Range Entangled Phases and Topology

Many-Body Localization in translation invariant systems?

Firewalls- A GR perspective

Monogamy of entanglement and improved mean-field ansatz for spin lattices

Self-assembling tensor networks and holography in disordered spin chains

Infinite Chiral Symmetry in Four Dimensions

Scalar Simplified Models and Dark Matter at Colliders

Cosmic flows: testing gravity and the matter power spectrum on very large scales

Maximal supergravity, holography and the Romans mass

Stripes and pairing in t-J and Hubbard models

Force-Free Electrodynamics around Extreme Kerr Black Holes

An invariant of topologically ordered states under local unitary transformations

Short-Range Entangled Phases and Topology

Many-Body Localization in translation invariant systems?

Firewalls- A GR perspective

Monogamy of entanglement and improved mean-field ansatz for spin lattices