Talks

10021 - 10032 of 16890 Results

13/14 PSI - Condensed Matter - Lecture 2

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 12, 2013

PIRSA:13110028
13/14 PSI - Quantum Field Theory II - Lecture 2

Francois David CEA Saclay

November 12, 2013

PIRSA:13110009
A universal Hamiltonian simulator: the full characterization

Gemma De Las Cuevas Universität Innsbruck

November 11, 2013

PIRSA:13110065

Quantum Information
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT

November 11, 2013

PIRSA:13110081

Cosmology
13/14 PSI - Condensed Matter - Lecture 1

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 11, 2013

PIRSA:13110027
13/14 PSI - Quantum Field Theory II - Lecture 1

Francois David CEA Saclay

November 11, 2013

PIRSA:13110008
Discussion

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 08, 2013

PIRSA:13110079
Twist Defects in Topological Systems with Anyonic Symmetries

Jeffrey Teo University of Illinois Urbana-Champaign

November 08, 2013

PIRSA:13110078
Quantum and Classical Anomalies

Michael Stone University of Illinois Urbana-Champaign

November 08, 2013

PIRSA:13110077
Majorana State Properties in Semiconductor and Oxide Superconducting Quantum Wires

Allan MacDonald The University of Texas at Austin

November 08, 2013

PIRSA:13110076
Discussion

Eduardo Fradkin University of Illinois Urbana-Champaign

November 07, 2013

PIRSA:13110075
Quantum quenches & holography

Robert Myers Perimeter Institute for Theoretical Physics

November 07, 2013

PIRSA:13110074

13/14 PSI - Condensed Matter - Lecture 2

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 12, 2013

PIRSA:13110028
13/14 PSI - Quantum Field Theory II - Lecture 2

Francois David CEA Saclay

November 12, 2013

PIRSA:13110009
A universal Hamiltonian simulator: the full characterization

Gemma De Las Cuevas Universität Innsbruck

November 11, 2013

PIRSA:13110065

Quantum Information

We show that if the ground state energy problem of a classical spin model is NP-hard, then there exists a choice parameters of the model such that its low energy spectrum coincides with the spectrum of \emph{any} other model, and, furthermore, the corresponding eigenstates match on a subset of its spins. This implies that all spin physics, for example all possible universality classes, arise in a single model. The latter property was recently introduced and called ``Hamiltonian completeness'', and it was shown that several different models had this property. We thus show that Hamiltonian completeness is essentially equivalent to the more familiar complexity-theoretic notion of NP-completeness. Additionally, we also show that Hamiltonian completeness implies that the partition functions are the same. These results allow us to prove that the 2D Ising model with fields is Hamiltonian complete, which is substantially simpler than the previous examples of complete Hamiltonians. Joint work with Toby Cubitt.
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT

November 11, 2013

PIRSA:13110081

Cosmology

Galaxy clusters form from the rarest peaks in the initial matter distribution, and hence are a sensitive probe of the amplitude of density fluctuations (sigma_8), the amount of matter in the universe, and the growth rate of structure. Galaxy clusters have the potential to constrain dark energy and neutrino masses. However, cluster cosmology is currently limited by systematic uncertainties due to poorly understood intracluster gas physics. I will present new statistical approaches to understand clusters and improve their cosmological constraining power through the thermal Sunyaev-Zel'dovich (tSZ) effect. First, I will describe a forthcoming first detection of the cross-correlation of the tSZ signal reconstructed from Planck data with the large-scale matter distribution traced by the Planck CMB lensing potential. This statistic measures the amount of hot gas found in moderately massive groups and clusters (M ~ 10^13-10^14.5 M_sun), a mass scale below that probed by direct cluster detections. Second, I will describe the first measurement of the PDF of the tSZ field using ACT 148 GHz maps. This measurement contains information from all (zero-lag) moments of the tSZ field, beyond simply the 2- or 3-point functions. It is a very sensitive probe of sigma_8 and may also provide a method with which to break the degeneracy between sigma_8 and uncertainties in the physics of the intracluster gas.
13/14 PSI - Condensed Matter - Lecture 1

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 11, 2013

PIRSA:13110027
13/14 PSI - Quantum Field Theory II - Lecture 1

Francois David CEA Saclay

November 11, 2013

PIRSA:13110008
Discussion

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

November 08, 2013

PIRSA:13110079
Twist Defects in Topological Systems with Anyonic Symmetries

Jeffrey Teo University of Illinois Urbana-Champaign

November 08, 2013

PIRSA:13110078

Twist defects are point-like objects that support robust non-local storage of quantum information and non-abelian unitary operations. Unlike quantum deconfined anyonic excitations, they rely on symmetry rather than a non-abelian topological order. Zero energy Majorana bound states can arise at lattice defects, such as disclinations and dislocations, in a topological crystalline superconductor. More general parafermion bound state can appear as twist defects in a topological phase with an anyonic symmetry, such as a bilayer fractional quantum Hall state and the Kitaev toric code. They are however fundamentally different from quantum anyonic excitations in a true topological phase. This is demonstrated by their unconventional exchange and braiding behavior, which is characterized by a modified spin statistics theorem and modular invariance.
Quantum and Classical Anomalies

Michael Stone University of Illinois Urbana-Champaign

November 08, 2013

PIRSA:13110077

I will begin reviewing the Callan-Harvey mechanism of anomaly inflow with particular focus on topological edge states and show how the inflow picture naturally converts the non-covariant "consistent" gauge anomaly of Bardeen and Zumino to the more physical "covariant" anomaly. I will then discuss some recent derivations of the covariant form of the gauge anomaly from classical phase space flows.
Majorana State Properties in Semiconductor and Oxide Superconducting Quantum Wires

Allan MacDonald The University of Texas at Austin

November 08, 2013

PIRSA:13110076

When proximity coupled to s-wave superconductors, quantum wires can support effective p-wave superconductivity under appropriate circumstances. The p-wave state has Majorana states at the wire ends which can store quantum information. I will discuss some properties of Majorana states formed in oxide and semiconductor quantum wires, including superconducting state phase diagrams as a function of spin-orbit coupling strength, Fermi energy, and external magnetic field strength, and Majorana exchange properties.
Discussion

Eduardo Fradkin University of Illinois Urbana-Champaign

November 07, 2013

PIRSA:13110075
Quantum quenches & holography

Robert Myers Perimeter Institute for Theoretical Physics

November 07, 2013

PIRSA:13110074

We employ holographic techniques to study quantum quenches at finite temperature, where the quenches involve varying the coupling of the boundary theory to a relevant operator with an arbitrary conformal dimension. The evolution of the system is studied by evaluating the expectation value of the quenched operator and the stress tensor throughout the process. The time dependence of the new coupling is characterized by a fixed timescale and the response of the observables depends on the ratio of the this timescale to the initial temperature. The observables exhibit universal scaling behaviours when the transitions are either fast or slow, i.e., when this ratio is very small or very large. For fast quenches, we uncover a universal scaling behaviour in the response of the system, which depends only on the conformal dimension of the quenched operator in the vicinity of the ultraviolet fixed point of the theory.

Title	Date	Collection	Type	Info
13/14 PSI - Condensed Matter - Lecture 2	2013‑11‑12	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 2	2013‑11‑12	13/14 PSI - Quantum Field Theory II	Course	View details
A universal Hamiltonian simulator: the full characterization	2013‑11‑11	Perimeter Institute Quantum Discussions	Scientific Series	View details
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT	2013‑11‑11	Cosmology and Gravitation	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 1	2013‑11‑11	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 1	2013‑11‑11	13/14 PSI - Quantum Field Theory II	Course	View details
Discussion	2013‑11‑08	PI-UIUC 2013	Conference	View details
Twist Defects in Topological Systems with Anyonic Symmetries	2013‑11‑08	PI-UIUC 2013	Conference	View details
Quantum and Classical Anomalies	2013‑11‑08	PI-UIUC 2013	Conference	View details
Majorana State Properties in Semiconductor and Oxide Superconducting Quantum Wires	2013‑11‑08	PI-UIUC 2013	Conference	View details
Discussion	2013‑11‑07	PI-UIUC 2013	Conference	View details
Quantum quenches & holography	2013‑11‑07	PI-UIUC 2013	Conference	View details

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