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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
General Relativity for Cosmology - Lecture 16

Achim Kempf University of Waterloo

November 07, 2013

PIRSA:13110004
Many-body localization: entanglement, emergent conservation laws, and the structure of eigenstates

Dmitry Abanin Princeton University

November 07, 2013

PIRSA:13110073
Matter matters in asymptotically safe quantum gravity
November 07, 2013

PIRSA:13110048
Quantum Gravity
Topological Phases in Transition Metal Oxides

Gregory Fiete

November 07, 2013

PIRSA:13110072
Dynamical Emergence of Universal Horizons during the formation of Black Holes

Mehdi Saravani Goldman Sachs (United States)
November 07, 2013

PIRSA:13110087
Strong Gravity
Entanglement at strongly-interacting quantum critical points

Roger Melko University of Waterloo

November 07, 2013

PIRSA:13110071

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.
General Relativity for Cosmology - Lecture 16

Achim Kempf University of Waterloo

November 07, 2013

PIRSA:13110004
Many-body localization: entanglement, emergent conservation laws, and the structure of eigenstates

Dmitry Abanin Princeton University

November 07, 2013

PIRSA:13110073
Matter matters in asymptotically safe quantum gravity
November 07, 2013

PIRSA:13110048
Quantum Gravity
The Functional Renormalisation Group technique has received great attention in recent times proving itself as a powerful tool to describe the high energy behaviour of gravitational interactions.
Its key ingredient is a nontrivial fixed point of the theory renormalization group flow which controls the behavior of the coupling constants in the ultraviolet regime and ensures that physical quantities are safe from divergences. I will briefly review the main ingredients of the gravitational asymptotic safety framework before focusing on the effect of massless minimally coupled scalars, fermions and vector fields on the gravitational fixed point. I will then set bounds on the type and number of such fields requiring the existence of a UV attractive fixed point. I will also discuss the dynamically generated quantum-gravity scale in asymptotic safety, which is the transition scale to the fixed-point regime, and its variation as a function of matter degrees of freedom. To conclude I will also consider the case of higher dimensional models.
Topological Phases in Transition Metal Oxides

Gregory Fiete

November 07, 2013

PIRSA:13110072

Certain varieties of transition metal oxides possess both significant interactions and strong spin-orbit coupling. In this talk I will describe materials-motivated models that predict topological phases in heterostructured and bulk transition metal oxides. We find Z2 topological insulators, Chern insulators, topological crystalline insulators, and interaction-driven topological phases not adiabatically connected to non-interacting topological phases.
Dynamical Emergence of Universal Horizons during the formation of Black Holes

Mehdi Saravani Goldman Sachs (United States)
November 07, 2013

PIRSA:13110087
Strong Gravity
In many theories with fundamental preferred frame, such as Einstein-Aether or Gravitational Aether theories, K-essence, Cuscuton theory, Shape Dynamics, or (non-projectable) Horava-Lifshitz gravity, the low energy theory contains a fluid with superluminal or incompressible excitations. In this talk, I study the formation of black holes in the presence of such a fluid. In particular, I focus on the incompressible limit of the fluid (or Constant Mean Curvature foliation) in the space-time of a spherically collapsing shell within an asymptotically cosmological space-time. In this case, I show that an observer inside 3/4 of the Schwarzschild radius cannot send a signal outside, after a stage in collapse, even using signals that propagate infinitely fast in the preferred frame. This confirms the dynamical emergence of universal horizons that have been previously found in static solutions [arXiv:1110.2195, arXiv:1104.2889, arXiv:1212.1334].
Entanglement at strongly-interacting quantum critical points

Roger Melko University of Waterloo

November 07, 2013

PIRSA:13110071

At a quantum critical point (QCP) in two or more spatial dimensions, leading-order contributions to the scaling of entanglement entropy typically follow the "area" law, while sub-leading behavior contains universal physics. Different universal functions can be access through entangling subregions of different geometries. For example, for polygonal shaped subregions, quantum field theories have demonstrated that the sub-leading scaling is logarithmic, with a universal coefficient dependent on the number of vertices in the polygon. Although such universal quantities are routinely studied in non-interacting field theories, it requires numerical simulation to access them in interacting theories. In this talk, we discuss numerical calculations of the Renyi entropies at QCPs in 2D quantum lattice models. We calculate the universal coefficient of the vertex-induced logarithmic scaling term, and compare to non-interacting field theory calculations. Also, we examine the shape dependence of the Renyi entropy for finite-size lattices with smooth subregion boundaries. Such geometries provide a sensitive probe of the gapless wavefunction in the thermodynamic limit, and give new universal quantities that could be examined by field-theoretical studies in 2+1D.

Title	Date	Collection	Type	Info
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
General Relativity for Cosmology - Lecture 16	2013‑11‑07	General Relativity for Cosmology - 2013	Course	View details
Many-body localization: entanglement, emergent conservation laws, and the structure of eigenstates	2013‑11‑07	PI-UIUC 2013	Conference	View details
Matter matters in asymptotically safe quantum gravity	2013‑11‑07	Quantum Gravity	Scientific Series	View details
Topological Phases in Transition Metal Oxides	2013‑11‑07	PI-UIUC 2013	Conference	View details
Dynamical Emergence of Universal Horizons during the formation of Black Holes	2013‑11‑07	Strong Gravity	Scientific Series	View details
Entanglement at strongly-interacting quantum critical points	2013‑11‑07	PI-UIUC 2013	Conference	View details

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