Search Talks

Search results from PIRSA

9337 - 9348 of 16424 Results

Applications of Information Theory in Direct Sum and Direct Product Problems
February 12, 2014

PIRSA:14020142
Quantum Physics
Quantum Tapestries

Matthew Fisher University of California, Santa Barbara

February 12, 2014

PIRSA:14020121
A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.

Max Metlitski Massachusetts Institute of Technology (MIT) - Department of Physics

February 12, 2014

PIRSA:14020120
13/14 PSI - Cosmology Review - Lecture 11

Latham Boyle University of Edinburgh

February 12, 2014

PIRSA:14020021
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

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

Applications of Information Theory in Direct Sum and Direct Product Problems
February 12, 2014

PIRSA:14020142
Quantum Physics
A fundamental question in complexity theory is how much resource is needed to solve k independent instances of a problem compared to the resource required to solve one instance. Suppose solving one instance of a problem with probability of correctness p, we require c units of some resource in a given model of computation. A direct sum theorem states that in order to compute k independent instances of a problem, it requires k times units of the resource needed to compute one instance. A strong direct product theorem states that, with o(k • c) units of the resource, one can only compute all the k instances correctly with probability exponentially small in k. In this talk, I am going to present some of recent progress on direct sum and direct product theorems in the model of communication complexity and two-prover one-round games with information-theoretic approach. The talk is based on parts of my doctoral work.
Quantum Tapestries

Matthew Fisher University of California, Santa Barbara

February 12, 2014

PIRSA:14020121

Within each of nature's crystals is an exotic quantum world of electrons weaving to and fro. Each crystal has it's own unique tapestry, as varied as the crystals themselves. In some crystals, the electrons weave an orderly quilt. Within others, the electrons are seemingly entwined in an entangled web of quantum motion. In this talk, I will describe the ongoing efforts to disentangle even nature's most intricate quantum embroidery. Cutting-edge quantum many-body simulations together with recent ideas from quantum information theory, such as entanglement entropy, are enabling a coherent picture to emerge.
A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.

Max Metlitski Massachusetts Institute of Technology (MIT) - Department of Physics

February 12, 2014

PIRSA:14020120

A 3d electron topological insulator (ETI) is a phase of matter protected by particle-number conservation and time-reversal symmetry. It was previously believed that the surface of an ETI must be gapless unless one of these symmetries is broken. A well-known symmetry-preserving, gapless surface termination of an ETI supports an odd number of Dirac cones. In this talk, I will show that in the presence of strong interactions, an ETI surface can actually be gapped and symmetry preserving, at the cost of carrying an intrinsic two-dimensional topological order. I will argue that such a topologically ordered phase can be obtained from the surface superconductor by proliferating the flux 2hc/e vortex. The resulting topological order consists of two sectors: a Moore-Read sector, which supports non-Abelian charge e/4 anyons, and an Abelian anti-semion sector, which is electrically neutral. The time-reversal and particle number symmetries are realized in this surface phase in an "anomalous" way: one which is impossible in a strictly 2d system. If time permits, I will discuss related results on topologically ordered surface phases of 3d topological superconductors.
13/14 PSI - Cosmology Review - Lecture 11

Latham Boyle University of Edinburgh

February 12, 2014

PIRSA:14020021
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

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.

Title	Date	Collection	Type	Info
Applications of Information Theory in Direct Sum and Direct Product Problems	2014‑02‑12	Perimeter Institute Quantum Discussions	Scientific Series	View details
Quantum Tapestries	2014‑02‑12	Emergence in Complex Systems	Conference	View details
A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.	2014‑02‑12	Emergence in Complex Systems	Conference	View details
13/14 PSI - Cosmology Review - Lecture 11	2014‑02‑12	13/14 PSI - Cosmology Review	Course	View details
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

Supported by

Format results

Applications of Information Theory in Direct Sum and Direct Product Problems

Quantum Tapestries

A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.

13/14 PSI - Cosmology Review - Lecture 11

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

Applications of Information Theory in Direct Sum and Direct Product Problems

Quantum Tapestries

A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.

13/14 PSI - Cosmology Review - Lecture 11

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