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TQFTs and Topological Phases of Matter

Zhenghan Wang Microsoft Corporation
May 06, 2013

PIRSA:13050022
Mathematical physics
3d boson topological insulators and quantum spin liquids

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
May 06, 2013

PIRSA:13050021
Condensed Matter
From Pauli's Principle to Fermionic Entanglement

Matthias Christandl ETH Zurich
May 03, 2013

PIRSA:13050005
Quantum Information

Quantum Foundations
AMS02 results support the secondary origin of cosmic ray positrons

Kfir Blum
May 03, 2013

PIRSA:13050015
Particle Physics
An Infalling Observer in AdS/CFT and the Information Paradox

Suvrat Raju
May 03, 2013

PIRSA:13050016
Quantum Fields and Strings
Dangerous Curves: How I Learned To Stop Worrying and Love the Calculus

Jennifer Ouellette Freelance Writer

May 01, 2013

PIRSA:13050004
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Baskaran Ganapathy Institute of Mathematical Sciences
April 30, 2013

PIRSA:13040140
Condensed Matter
Quantum measurements constrained by symmetry

Leon Loveridge University of York
April 30, 2013

PIRSA:13040124
Quantum Foundations
Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University
April 30, 2013

PIRSA:13040141
Quantum Fields and Strings
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington
April 30, 2013

PIRSA:13040126
Particle Physics
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London
April 30, 2013

PIRSA:13040128
Cosmology
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong
April 29, 2013

PIRSA:13040112
Quantum Foundations

TQFTs and Topological Phases of Matter

Zhenghan Wang Microsoft Corporation
May 06, 2013

PIRSA:13050022
Mathematical physics
In two spatial dimensions, there is a good correspondence between TQFTs and topological phases of matter for spin systems. I will discuss this correspondence in one and three spatial dimensions for spin systems. If time permits, I will also discuss the situation for fermion systems.
3d boson topological insulators and quantum spin liquids

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
May 06, 2013

PIRSA:13050021
Condensed Matter
I will discuss recent work on 3d Symmetry Protected Topological (SPT) phases of bosonic systems, and their implications for understanding the more exotic quantum spin liquid phases. First I will describe various characterizations of these 3d SPT phases, in particular their surface effective theories and (when applicable) bulk electromagnetic response. Next I will show how this understanding leads to several new insights into the theory of both 2d and 3d quantum spin liquids. Finally I will provide an explicit construction of several 3d SPT phases in a system of `coupled layers'. This includes a 3d SPT state that is beyond the existing cohomology classification of such states.
From Pauli's Principle to Fermionic Entanglement

Matthias Christandl ETH Zurich
May 03, 2013

PIRSA:13050005
Quantum Information

Quantum Foundations
The Pauli exclusion principle is a constraint on the natural occupation numbers of fermionic states. It has been suspected for decades, and only proved very recently, that there is a multitude of further constraints on these numbers, generalizing the Pauli principle. Surprisingly, these constraints are linear: they cut out a geometric object known as a polytope. This is a beautiful mathematical result, but are there systems whose physics is governed by these constraints? In order to address this question, we studied a system of a few fermions connected by springs. As we varied the spring constant, the occupation numbers moved within the polytope. The path they traced hugs very close to the boundary of the polytope, suggesting that the generalized constraints affect the system. I will mention the implications of these findings for the structure of few-fermion ground states and then discuss the relation between the geometry of the polytope and different types of fermionic entanglement.
AMS02 results support the secondary origin of cosmic ray positrons

Kfir Blum
May 03, 2013

PIRSA:13050015
Particle Physics
We show that the recent AMS02 positron fraction measurement is perfectly consistent with a secondary origin for positrons, and does not require additional primary sources such as pulsars or dark matter. Within the secondary model the AMS02 data imply a cosmic ray propagation time in the
Galaxy of about one Myr and an average traversed interstellar matter density of about 1/cc at a rigidity of 300 GV. These results may hint that high energy cosmic rays are confined to a thin halo of scale height similar to the gaseous disk.
An Infalling Observer in AdS/CFT and the Information Paradox

Suvrat Raju
May 03, 2013

PIRSA:13050016
Quantum Fields and Strings
We reconstruct the experience of an infalling observer using the AdS/CFT correspondence. We write operators both outside and inside the black hole in terms of CFT operators. Our construction provides a natural realization of black hole complementarity, and a way of preserving information without the need for firewalls.
Dangerous Curves: How I Learned To Stop Worrying and Love the Calculus

Jennifer Ouellette Freelance Writer

May 01, 2013

PIRSA:13050004

Based on her book, The Calculus Diaries, join, Jennifer Ouellette as she shows how calculus can be applied to everything from gas mileage, diet, the rides at Disneyland, surfing in Hawaii, shooting craps in Vegas and warding off zombies. Even the mathematically challenged, can-and-should learn the fundamentals of the universal language.
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Baskaran Ganapathy Institute of Mathematical Sciences
April 30, 2013

PIRSA:13040140
Condensed Matter
Utilizing a variety and also constraints offered by quantum and solid state chemistry, we discuss possibilities of unconventional quantum magnetism and superconductivity in doped 3 dimensional Mott insulators. Some of the possibilities are quantum spin liquid states having pseudo fermi surface coexisting with long range magnetic order, 3 dimensional emergent gauge fields and unconventional superconducting order parameter symmetry. We present a few realistic models to illustrate this and use our theory to understand anomalous behavior of certain double perovskite compounds.
Quantum measurements constrained by symmetry

Leon Loveridge University of York
April 30, 2013

PIRSA:13040124
Quantum Foundations
The Wigner-Araki-Yanase (WAY) theorem delineates circumstances under which a class of quantum measurements is ruled out. Specifically, it states that any observable (given as a self adjoint operator) not commuting with an additive conserved quantity of a quantum system and measuring apparatus combined admits no repeatable measurements. I'll review the content of this theorem and present some new work which generalises and strengthens the existing results. The observation that the WAY constraint vanishes if the observable-to-be-measured is ``relativised'' (in a suitable sense) points to interesting links with quantum reference frames and superselection rules. I'll discuss some of these connections and raise some open questions.
Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University
April 30, 2013

PIRSA:13040141
Quantum Fields and Strings
It has been known for twenty years that a class of two-dimensional gauge theories are intimately connected to toric geometry, as well as to hypersurfaces or complete intersections in a toric varieties, and to generalizations thereof. Under renormalization group flow, the two-dimensional gauge theory flows to a conformal field theory that describes string propagation on the associated geometry. This provides a connection between certain quantities in the gauge theory and topological invariants of the associated geometry. In this talk, I will explain how recent results show that, for Calabi-Yau geometries, the partition function for each gauge theory computes the Kahler potential on the Kahler moduli of the associated geometry. The result is expressed in terms of a Barnes' integral and is readily evaluated in a series expansion around special points in the moduli space (e.g., large volume), providing a fairly efficient way to compute Gromov-Witten invariants of the associated geometry.
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington
April 30, 2013

PIRSA:13040126
Particle Physics
In this talk, I will start with briefly introducing some universal physics behind quantum hall and topological insulator , which inspired a BSM flavor model. It intimately relates deconstructed little Higgs to flavor structure: fermion masses, CKM etc. This new cousin of little Higgs, we call it little flavor, shares a 10-20 Tev cut-off scale with little Higgs, so as to explain flavor structure at surprisingly low scale without rising FCNC problem.
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London
April 30, 2013

PIRSA:13040128
Cosmology
The non-Gaussian statistics of the primordial density perturbation have become a key test of the inflationary scenario of the very early universe. Currently many techniques are used to calculate the non-Gaussian signatures of a given model of inflation. In particular, simple super-horizon techniques such as the deltaN formalism are often used for models with more than one field, while more technical field theory techniques, referred to as the In-In formalism, are typically used for models where the quantum sub-horizon evolution is important. Recently we have been developing an alternative point of view, called the transport approach. This framework highlights the connections between these other techniques and unifies them. Moreover, since it reduces the problem of calculating the statistics to that of solving a set of coupled ODEs, numerical implementations of the system are extremely simple.
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong
April 29, 2013

PIRSA:13040112
Quantum Foundations
A recent development in information theory is the generalisation of quantum Shannon information theory to the operationally motivated smooth entropy information theory, which originates in quantum cryptography research. In a series of papers the first steps have been taken towards creating a statistical mechanics based on smooth entropy information theory. This approach turns out to allow us to answer questions one might not have thought were possible in statistical mechanics, such as how much work one can extract in a given realisation, as a function of the failure-probability. This is in contrast to the standard approach which makes statements about average work. Here we formulate the laws of thermodynamics that this new approach gives rise to. We show in particular that the Second Law needs to be tightened. The new laws are motivated by our main quantitative result which states how much work one can extract or must invest in order to affect a given state change with a given probability of success. For systems composed of very large numbers of identical and uncorrelated subsystems, which we call the von Neumann regime, we recover the standard von Neumann entropy statements.

Joint work with Egloff, Renner and Vedral

http://arxiv.org/abs/1207.0434

Title	Date	Collection	Type	Info
TQFTs and Topological Phases of Matter	2013‑05‑06	Emergence & Entanglement II 2013	Conference	View details
3d boson topological insulators and quantum spin liquids	2013‑05‑06	Emergence & Entanglement II 2013	Conference	View details
From Pauli's Principle to Fermionic Entanglement	2013‑05‑03	Colloquium	Scientific Series	View details
AMS02 results support the secondary origin of cosmic ray positrons	2013‑05‑03		Scientific Series	View details
An Infalling Observer in AdS/CFT and the Information Paradox	2013‑05‑03	Quantum Fields and Strings	Scientific Series	View details
Dangerous Curves: How I Learned To Stop Worrying and Love the Calculus	2013‑05‑01	Public Lecture Series	Public Lectures	View details
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators	2013‑04‑30	Quantum Matter	Scientific Series	View details
Quantum measurements constrained by symmetry	2013‑04‑30	Quantum Foundations	Scientific Series	View details
Gromov-Witten Invariants from 2D Gauge Theories	2013‑04‑30	Quantum Fields and Strings	Scientific Series	View details
From topological insulator to weak scale flavor physics	2013‑04‑30	Particle Physics	Scientific Series	View details
Transporting non-Gaussianity from sub- to super- horizon scales	2013‑04‑30	Cosmology and Gravitation	Scientific Series	View details
Laws of thermodynamics beyond the von Neumann regime	2013‑04‑29	Perimeter Institute Quantum Discussions	Scientific Series	View details

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